get involved with NSHMBA early (national society of hispanic mbas). if you can get involved with your local chapter, you can apply to be a VP of your local chapter's board.
www.nshmba.orgalso, since you're still early in the game, i'd highly recommend you look into management leadership for tomorrow (MLT). it's very competitive to get in, but if you get accepted, it's a year long program that grooms you into a successful b-school candidate. many of the latinos and other URMs at top schools all graduated from this program (unfortunately, i was not aware of it, and so i did not apply).
www.ml4t.organother group to keep your eyes on is the toigo foundation.
www.toigofoundation.com finally, keep tabs on the consortium for graduate study in management (aka consortium, or CGSM). through the consortium, you are exposed to a large alumni network from students at top schools around the country. you also have the chance to be considered for a full tuition fellowship.
www.cgsm.org