Beezy, haven't you already beaten Mass Effect? Why would you want to replay it?
Anyways, I don't think I'd use a guide until I was stuck. Part of the fun in RPGs comes from figuring out the game on your own, like discovering the battle strategy that works, finding loot that are hidden, etc. Using a guide to play the game is almost like reading the synopsis of a film before watching it. The experience is just not as gratifying when the element of surprise is removed.