Pure warrior will not get you far as warrior class is limited to only melee damage and that is it. You either go support/warrior like chieftain, dragonslayer or merchant. Or go hybrid warrior/mage like tinker, ranger or master paladin. They give your hero a chance to be warrior and give support to units you produce to back him/her up or spells to backup your troops alongside.
As far as mages go you have to find your style of it. You can be a nasty thorn in your enemies by using diseased buildings and causing their diseased units/buildings to take damage by being blightlord or defiler, mostly indirect damage dealer. You can be direct damage dealer by being icemage/pyromancer/etc which deals direct damage, most spell spheres have summons.
Even healing sphere in the 0.8.9 will have a summon.
Play everything and get a feel for the class, race combinations will come along.