Marvel Origins/ DC Origins/ Web of Spiderman / SuperMan<>Man of Steel for boosters.
XMen/BrotherHood -- Gotham Knights/Arkhaim Inmates -- Spider Friends/Sinister Syndicate for starters.
That is your team/deck preference. I usually reccommend XMen/BH to my new guys and help them build offa that, as it is what I had the most of for spare cards.
I recommend hunting around the internet/sites and looking into different teams that are out. Decide what your interested in making, then focus on that set until you complete your deck. Then expand from there for trades/other decks.
Hope this helps...
Ciao!!