Are the tracks recorded with enough gain? When you look at the waves in the project view, you should have a pretty decent-sized wave for each track. If not, you need to record hotter.
If you have a track that was recorded too quietly, though, just use a Gain processor on it and bump it up 4dB at at time until it's loud enough for you.
Another thing you can do is toss a compressor on the track and squash it until it gets loud enough with makeup gain.