If your cycle is complete, you can certainly start to add inhabitants.
Originally posted by SMARTbomb
If coral, how many at a time?
I asked a similar question when starting my conversion to a reef tank. Apparently cost is the only real factor here as corals have very little bioload.
Originally posted by SMARTbomb
In 75 gal tank how many species should I go for?
Thats all up to you. I'd suggest looking through postings in the photography forum. There are some beautiful tank shots there that might give you some ideas.