pick up the most aggresive low cost creatures in your colours, there are lots of 1/2 costed creatures with two power, they are recommended. try to avoid powerful cards that cost more then four if you can get nice 1/2/3 drops or removels instead. you want 15+ creatures that have at least 12 drops that cost 4 or less, especially two drops in this format. Lots of creatures only get powerful during your turn or during attacks, so racing is very common and blocking isn't very effective.
The best creatures (and signals for colour) are kor skyfisher, kazanadu blademaster, vampire nighthawk, plated geopede and probably living tsunami. there are other good ones like Steppe Lynx, Kor Aeronaut, Windrider Eel, Umara Raptor, gatekeeper of malakir, welkin tern, Goblin Shortcutter, Goblin Bushwacker, kor hookmaster, vampire lacerator, and if you want grren you have: Oran-Rief Survivalist, Grazing Gladehart and Timbermaw Larva. probably bladetusk boar and the vampire that makes opponents lose life whenever they play creatures. These are all very good creature for an aggro deck and are what makes zendikar this crazy format, but they aren't as higly picked as the five I marked and are usually passed for them, for big finisher bombs and for decent removels so you can get more of these for picks 3-7 probably.
Aperatently if green is extremely avaliable you can get multiple copies of good aggressive green cards such including ones I forgot like river boa and turntimber basilisk.
[[kor skyfisher]] [[kazandu blademaster]] [[vampire nighthawk]] [[plated geopede]] [[living tsunami]]