I was Renegade but I had a good portion of Paragon points. I could say that they were 50-50, with Renegade taking the upper hand. Not playing Renegade is like not playing the game at all.
My Shepard was a cynical badass and had a "shoot first - ask questions later" philosophy, but he was nice to the team (I can't bring myself to be an ass to my crew, they're like a family to me.

) and non-annoying NPC's, e.g. Gianna Parasini (And she even kissed him for it, lol.) Also, romance gives you a ton of Paragon points.
I settled the dispute between Miranda and Jack with intimidate, I told Legion to back off when he almost got in a fight with Tali, but later I told him that I lied to her with intimidate and regained his loyalty.
It's more fun to act on your instinct, rather than to play straight Paragon or Renegade.