depends on how you plan to play in the future. if you want to go to FNMs and such this deck won't get you far there, but for casual play your fine.
As far as improvments. Try to find more creatures that can lower your curve.(http://wiki.mtgsalvation.com/article/Mana_curve). If you're doing RG you gotta pick up a set of burning tree emissary, experiment one, rakdos cakcler, ghorclan rampager. These cards are fairly inexpensive and will go a long way to getting where you want to be with your deck. Budget rares to look for are Rubblebelt raiders and the newly minted Savageborn Hydra. Try to stay under 4-5 cost for your highest cards.
Take a look at the list I have together for a jund (Red, black, Green) aggro. A lot of the creatures still apply to you. The mana is the most expensive thing in the deck but once you have it you have it.
http://deckbox.org/sets/349197