Comparing with Spanish 't', put the tip of tongue behind the upper teeth and press a bit to pronounce it, when it comes to 'd' sound, just put the tip of my tongue between the upper teeth and the lower teeth, I want to know if this method of pronouncing 'd' is right. Is there any other ways to pronounce the 'd' sound?
Depends where the d is located.
In front of the word or after a consonant:
- It is pronounced like you how pronounce it in English. Example: day = día, agenda = emprenda.
After a vowel
- It is pronounced like "th" as in "the". Example: edulcorante, educación.
At the end of the word
- It is pronounced like "th" as in "the". But in many dialects it is very relaxed. Examples: Madrid, usted, verdad. -But you can still find some people that pronounce the "d" at the end of the word as in Madrid-
Ends in -ado, -ido
- It is almost imperceptible. Examples: cansado, comido.
Important: This answer must be analyzed in its entire form. The statements are not by any means independent of each other.
The consonant D, in Spanish, is known as a dental consonant, because, well, your tongue presses against your teeth. Not to be confused with Alveolar consonants which would be above your teeth slightly, touching the alveoli (the back of the gum holes).
There are several other variations of that consonant within different dialects. Some pronounce it as (th), some pronounce is as a J sound (known as a post-alveolar consonant). The TH form is a labiodental consonant because the tongue touches both the teeth and the lips.
I think that the standard Spanish d is the same as the standard Spanish t, but with d being voiced, while t is voiceless.
That is, in both phonemes the tip of the tongue is pressed to the back of the upper teeth, but pointing slightly down. Maybe the part of the tongue just next to the tip is just[touching the alveolar ridge. It is actually a denti-alveolar consonant. Sometimes the tongue does not actually touch the teeth, so the consontant is not totally oclusive (approximant consonant).
If you put the tongue between the upper and lower teeth you will get a sound more like
/z/ instead of
/d/. That is usual and somewhat accepted for a d at the end of a word, such as in "Madrid" or "id" (imperative of "ir"), but not for other places.
In relaxed speech, particularly in intervocalic positions, the d sound is sometimes relaxed. This is done by keeping a gap between the tongue and the teeth (not lower the tongue) and preventing the stop of the air flow.
In extreme cases the d may even disappear, such as in "estoy cansa(d)o".
Note that the t sound cannot be relaxed this way, maybe because it is voiceless.