Hi there. This is the standard version of the other Mardu deck on my profile.
So basically, you want Mardu Ascendancy. Get that and you're good. If not... Well, you should be fine. Take a look!
Turn 1: Caves of Koilos then Bloodsoaked Champion.Turn 2: Any white source then Consul's Lieutenant, attack for 2.Turn 3: Any red source then Mardu Ascendancy attack for 4 (2 from Champion, 2 from Lieutenant), which becomes 6 with the 2 new Goblins. Lieutenant is Renowned.Turn 4: Any land then Valor in Akros. Attack with all your creatures. Lieutenant gives all of your creatures +1/+1, so that's 4 damage there. 1 per goblin, that's 6 now. 3 for Lieutenant, 2 for Champion, that's 11 now. You get 2 new goblins for attacking, adding 2 damage, (to make 13) triggering Valor twice. Each of your six creatures get +2/+2, which adds 12 damage. 25 damage on just that turn.
Obviously, that's a perfect hand, and perfect board. So I have Ultimate Price and Mardu Charm as removal. Mardu Charm can also be used rather effectively to block when combined with Valor in Akros. Dragon Fodder and Hordeling Outburst all work effectively with both Valor in Akros and Goblin Piledriver. Brutal Hordechief because you'll have a ton of creatures.
Are all their creatures there bugging you? Firemantle Mage may be of assistance. Depending on the number of multicoloured creatures, there's also Radiant Purge. Also, if necessary, there's Scab-Clan Berserkers. Have fun.