For dry flies and wet flies in water that's neither very deep nor with a lot of current, a floating weight forward or double taper line will probably serve you just fine. I personally believe a weight forward line casts better in most situations. With floating lines and wet flies and steamers, the old fashioned way is to put some wet fly dressing on the wet fly to make it sink. But, keep in mind that if there is a swift current, that's not going to be enough to get your wet fly to sink as it swings around...for current and wet flies, go with a sink tip line. A line that sinks 3-4 inches per second should do the trick. The faster and deeper the river, the "faster" (sinking) your sink tip line should be.
There are a lot of fine lines on the market. Buy a good one (or two). Premium lines last longer and cast better. Scientific Anglers, Rio and Cortland make some of the best lines around and I'd recommend you start with one of those. A good line costs about $50-60, but is worth it if you plan to stick with fly fishing.
Well good luck and hope this helps!
Zugbugz - Arizona Go