Are you going to pvp or pve? but sadly ur going to have to get at least 3-4 accounts to be really successful

for pvp- ur going to need all the same class.. successfully u can reach 2.5k in arenas.. the best comp for this is 4-5 shamans
for pve- u can get differnet kinds of classes.. but its a little more complicated. You can successfully run with 4 shamans and 1 tank friend. chain healx4=ftw. this will solve ur problem if u have a tank that will run with u whereever u go.