How to Change Your Handwriting
If you want to change your handwriting, start by finding a pen that fits comfortably in your hand. This will help you be able to guide the pen over the paper more smoothly. Take your time when you're writing, and don't press too hard with the pen, or you'll end up writing crooked letters. While you're writing, sit up at a table with your back and arm straight so you will have more control over the pen, and take time to practice your handwriting every day.
Find the right pen. The right pen will be different for each person, but in general, you should look for one that flows well and that you won't grip too tightly. Larger grips can help you loosen your grip. Take your time. Good handwriting takes time, and if you rush through it, your writing will be sloppy. If you catch yourself being sloppy, take a deep breath, slow down, and start again. Practice good posture. Sit up at a table with your back and arm straight. Don't grip the pen or pencil too hard, as that can make your hand cramp. Try air writing. This method teaches you to write with your arm instead of drawing the letters with your finger, making for better writing. Holding your hand in the air, mostly use your forearm and shoulder to write large letters in the air. This practice will help you feel what muscles you should be using when you write. Move to smaller letters in the air. Use paper. When you first move to paper, try simple strokes like circles and slashes. Keep them as evenly spaced as possible, while still using the muscles in your arm. Don't press too hard. Pressing too hard can lead to crooked letters. Instead, lift up a bit and let the letters flow smoothly. Practice daily. Take some time each day to actually use your handwriting. One easy way to get your practice in is to keep a daily journal. Write about what happens in your day or what you're feeling. Check out each letter. Do any of them look squished or not formed correctly? Practice writing that letter in good form by comparing it to an online chart. Use bigger letters. For a period of time, try using bigger letters when you write. That way, you can see if you are making letters in the right way, and you can correct as you go. One way to encourage larger writing is to use wide-ruled paper. Look at the heights of your letters. Your letters should all come up to about the same height, and any descenders should go about the same length below the line. For instance, your lowercase "g" and "y" should go down about the same length. Also, they shouldn't be cramping the line below. Use a ruler to check your height. If you lay it across the top of your uppercase and lowercase letters, you can see if you make certain letters shorter or taller. Watch out for spacing. Make sure you aren't spacing your letters too far apart or too close together. Half of a lowercase "o" should fit between letters, no more. Go back to school. That is, if you want a new style of writing, you need to relearn the way you write, which won't be that different from the way you learned to write as a kid. Find a font you like. You can use font sites to find a font that you admire or even just use your word processing software. Print off the font in lowercase and uppercase letters. You can also include pangrams such as "The quick brown fox jumps over the lazy dog." Pangrams are texts that contain every letter in the English language, so they are good for practice. Start out using a larger size for your font, such as 14 point. Use tracing paper or other lightweight paper. Place the paper over the page you printed. Trace over the letters with a pen or pencil. Move on to copying. Once you've traced the letters a few times, move on to copying the letters by looking at the letters and trying to write sentences. This forces you to look at how the letters are actually formed. Try it on your own. Without looking at the font, try writing in the same style. Though it will not perfectly match the original, you will be using a different handwriting style. Practice the font. To make the font your own, you must practice it often. Try writing in a journal or writing out your grocery list in that style. Over time, it will feel more natural. 
Find the right pen. Take your time. Practice good posture. Try air writing. Don't press too hard. Practice daily. Check out each letter. Use bigger letters. Look at the heights of your letters. Watch out for spacing. Go back to school. Find a font you like. Print off the font in lowercase and uppercase letters. Use tracing paper or other lightweight paper. Move on to copying. Try it on your own. Practice the font. 