Hello, I'm trying to figure out the different pronounciations of the hiragana, so far I've found the r's, and the d's (ra, ri, ru, re, ro, di, du) to sound a bit different, are there any more I should know about, and how do I correctly say them?

the r's seem to sound like rl and then the vowel, is this correct?

and the 2 d's sound like dz?

thanks