As in many games with moral choice, the best way (game wise) is to go all out on either. This often puts you in a situation where you turn out to be either Mother Teresa or Vlad the Impaler. Staying somewhere in the middle locks you out of either bonuses. But at the same time it makes for more interesting role playing.
I'm playing through ME1 now and I'm going the Paragon
route. Playing a nice Shepard is mostly rewarding (and it's the way I like him) but ever so often, I get into a situation where I really would like to slap faces. But because of the Charm/Intimidate skills I still choose the Paragon option.
This is getting really annoying because while a Paragon Shepard is a nice person to play, he also seem to be pushed around by everyone and their mum - i.e. he's a complete wuss.
Can I still receive full Charm while mixing in a few Renegade points when I feel like it?