May I Invest as a non accredited investor?
Does me holding stock in the company make me an accredited investor with this company in particular? No.  But maybe the site will let you trade it your shares to another accredited investor. Just ask, if the site operators have a securities lawyer they should be able to accomodate Without knowing the specifics it is hard to give you a specific answer, but most likely the answer is no. If they limit the participation in the site to accredited investors, this is probably not something they are doing willingly, but rather imposed by regulators. Acredited investors have access to instruments that don't have the same level of regulatory protection & scrutiny as those offered to the general public, and are defined under Regulation D.  Examples of such securities are 144A Shares, or hedgefunds.
Ben Miller's answer is very thorough, and I up voted it. I believe that the ability to rebalance without tax implications is very import, but there are two aspects of the question that were not covered: The 401K in many cases comes with a company match. Putting enough money into the fund each year to maximize the match, give you free money that is not available in the non-retirement accounts. The presence of that match is to encourage employees to contribute: even if they are tying up their funds until retirement age; and they are into a plan with only a handful of investment options; and they may have higher expenses in the 401K. The question also had a concern about the annual limits for the 401K (18,000) and the IRA (5,500). The use of a retirement account doesn't in any way limit your ability to invest in non-retirement accounts. You can choose to invest from 0 to 23,500 in the retirement accounts and from 0 to unlimited into the non-retirement accounts. Double those amounts if you are married. What are the risks pertaining to timing on long term index   investments? The risks are countless for any investment strategy.  If you invest in US stocks, and prices revert to the long term cyclically adjusted average, you will lose a lot of money.  If you invest in cash, inflation may outpace interest rates and you will lose money.  If you invest in gold, the price might go down and you will lose money.  It's best to study history and make a reasonable decision (i.e. invest in stocks). Here are long term returns by asset class, computed by Jeremy Siegel:  $1 invested in equities in 1801 equals $15.22 today if was not invested and $8.8 million if it was invested in stocks.  This is the 'magic of compound interest' and cash / bonds have not been nearly as magical as stocks historically. 2) How large are these risks? The following chart shows the largest drawdowns (decreases in the value of an asset) since 1970 (source):  Asset prices decrease in value frequently.  Financial assets are volatile, but historically, they have increased over time, enabling investors to earn compounded returns (exponential growth of money is how to get rich).  I personally view drawdowns as an excellent time to buy - it's like going on a shopping spree when everything in the store is discounted. 3) In case I feel not prepared to take these risks, how can I avoid   them? The optimal asset allocation depends on the ability to take risk and your tolerance for risk.  You are young and have a long investment horizon, so if stocks go down, you will have plenty of time to wait for them to go back up (if you're smart, you'll buy more stocks when they go down because they're cheap), so your ability to bear risk is high.  From your description, it seems like you have a low risk tolerance (despite a high ability to be exposed to risk).  Here's the return of various asset classes and how the average investor has fared over the last 20 years (source):  Get educated (read Common Sense on Mutual Funds, A Random Walk Down Wall Street, etc.) and don't be average! Closing words: Investing in a globally diversified portfolio with a dollar cost averaging strategy is the best strategy for most investors.  For investors that are unable to stay rational when markets are volatile (i.e. the investor uncontrollably sells their stocks when stocks decrease 20%), a more conservative asset allocation is recommended.  Due to the nature of compounded interest, a conservative portfolio is likely to have a much lower future value. SecondMarket attempts to add liquidity to privately held companies. You may be able to find a buyer there, but this is still incredibly illiquid due to accredited investor regulations constricting businesses from catering to the 99%. As around 1% of the United States population qualifies as an accredited investor. Properties do in fact devaluate every year for several reasons. One of the reasons is that an old property is not the state of the art and cannot therefore compete with the newest properties, e.g. energy efficiency may be outdated. Second reason is that the property becomes older and thus it is more likely that it requires expensive repairs. I have read somewhere that the real value depreciation of properties if left practically unmaintained (i.e. only the repairs that have to absolutely be performed are made) is about 2% per year, but do not remember the source right now. However, Properties (or more accurately, the tenants) do pay you rent, and it is possible in some cases that rent more than pays for the possible depreciation in value. For example, you could ask whether car leasing is a poor business because cars depreciate in value. Obviously it is not, as the leasing payments more than make for the value depreciation. However, I would not recommend properties as an investment if you have only small sums of money. The reasons are manyfold: So, as a summary: for large investors property investments may be a good idea because large investors have the ability to diversify. However, large investors often use debt leverage so it is a very good question why they don't simply invest in stocks with no debt leverage. For small investors, property investments do not often make sense. If you nevertheless do property investments, remember the diversification, also in time. So, purchase different kinds of properties and purchase them in different times. Putting a million USD to properties at one point of time is very risky, because property prices can rise or fall as time goes on. You are always best off investing in things you understand. If you have a deep understanding of the aeronautical industry, say, you are a Vice President at Boeing and have been working at Boeing for 40 years, then that would be a reason for investing in that sector: because you may be able to better evaluate different companies in that sector. If you are a novice in the sector, or just have an amateur interest in it, then it may not be a good idea, because your knowledge may not be sufficient to give you much of an advantage. Before focusing on one investment of any type, industry sector based, or otherwise, you want to ask yourself: am I an expert in this subject? The answer to that question will have a big impact on your success. Avoiding tobacco, etc is fairly standard for a fund claiming ethical investing, though it varies. The hard one on your list is loans.  You might want to check out Islamic mutual funds. Charging interest is against Sharia law.  For example: http://www.saturna.com/amana/index.shtml From their about page: Our Funds favor companies with low price-to-earnings multiples, strong   balance sheets, and proven businesses. They follow a value-oriented   approach consistent with Islamic finance principles. Generally, these   principles require that investors avoid interest and investments in   businesses such as liquor, pornography, gambling, and banks. The Funds   avoid bonds and other conventional fixed-income securities. So, it looks like it's got your list covered.  (Not a recommendation, btw. I know nothing about Amana's performance.) Edit: A little more detail of their philosophy from Amana's growth fund page: Generally, Islamic principles require that investors share in profit   and loss, that they receive no usury or interest, and that they do not   invest in a business that is prohibited by Islamic principles. Some of   the businesses not permitted are liquor, wine, casinos, pornography,   insurance, gambling, pork processing, and interest-based banks or   finance associations. The Growth Fund does not make any investments that pay interest. In   accordance with Islamic principles, the Fund shall not purchase   conventional bonds, debentures, or other interest-paying obligations   of indebtedness. Islamic principles discourage speculation, and the   Fund tends to hold investments for several years. Who is going to invest without being a gatekeeper? You don't invest in stuff you don't think is good ... as an investor, you will select who you invest in. You don't invest and sit back and not provide any input on what you think the artist should do to sell themselves so that you make your money back. Since you mention the religion restriction, you should probably look into the stock market or funds investing in it. Owning stock basically means you own a part of a company and benefit from any increase in value the company may have (and 'loose' on decreases, provided you sell your stock) and you also earn dividends over the company's profit. If you do your research properly and buy into stable companies you shouldn't need to bother about temporary market movements or crashes (do pay attention to deterioration on the businesses you own though). When buying stocks you should be aiming for the very long run. As mentioned by Victor, do your research, I recommend you start it by looking into 'value stocks' should you choose that path.