Final Fantasy 12 team help plz?

only 3 hours into Final fantasy 12 for ps2. trying to figure out what team set up i want. i decided im only gonna lvl 3 guys. not 6. i need help figuring out how to set up my team. I want Vaan as my tank but do i give him white magic cus then enemies will stay attracted to him not only cus hes tank but with healing spells he will attract the enemy? or should i do Vaan as tank(sword shield) and Penelo as both my black and white mage? and then ether have Basch as a 2h sword dps/ Balthier or Fran as a ranger dps? please help me haha im pretty new to final fantasy. how should i set up my 3 guys. i dont see the point in having Vaan as a tank if my mage who does black and white magic pulls all the aggro ya knw? i might as well just have no tank. im guessing im not geting how to do this hahah