Acropora, In my opinion, is the most difficult genus of Small polyped scleractinian. As other Small polyped scleractinians require, strong water flow, a
matured tank (preferably over 7 months old, a year would be better), stable calcium and alkalinity level, Stable temperature, outstanding water quality, and (preferably) halides. I would say halides are nessisary for sucessfull acropora husbandry. If you're going to be keeping corals in the genus Acropora (or possibly in the Family Acroporidea), you should have a good amount of metal halides.
If you're just starting out, you should first wait until your tank has matured (as stated above, over 7 months old) and your tank has all the proper equiptment. Once you have the proper equiptment, you could try the easy-to-keep Small polyped scleractinians. These include many Montipora varieties, Pavona, Hydnophora, etc. Once you've had great sucess with those, you could try your first Acropora. I would personally recommend the A. Yongei (or also known as the Green Slimmer, Bali Slimmer, Green staghorn, etc.). If that does good over a period of several months (a few weeks won't tell you if it's thriving or not), you could slowely move to other SPS corals.
stoney based corals
Calcium Carbonate Based corals
they are noted for fast growth
Not all Small polyped scleractinians are noted for extremely fast growth. Some barley grow at all within a year, such as the Purple Monster(© Steve Tyree
).
I think it would really help if you gave us some of your tank information. The more information you provide, the better.
Take Care,
Graham