I'd like to add to this, if I may...
Once you are comfortable with fingering solidly, like Uriah was saying, try this finger exercise to build speed and accuracy (this works both hands, too).
Start on the top (big E) string, and play the 1st, 2nd, 3rd, 4th frets with those fingers (1st fret--1st finger, 2nd fret--2nd finger, etc.). As you do this, concentrate on alternate picking with your pick hand. 1st fret pick down, 2nd fret pick up, 3rd fret pick down, 4th fret pick up. Work this on all the strings, then do it backwards back to the low E string (4, 3, 2, 1). If you do thi exercise everyday to the 5th fret and back you will see your fingers getting crazy-strong and your accuracy when going after a note will be off the charts.
If y'all read TAB, it looks like this (remember to alternately pick):
---------------------------------------------------1-2-3-4---4-3-2-1------------
-----------------------------------------1-2-3-4-----------------------4-3-2-1--
-------------------------------1-2-3-4-------------------------------------------
---------------------1-2-3-4-----------------------------------------------------
-----------1-2-3-4----------------------------------------------------------------
-1-2-3-4-------------------------------------------------------------------------
and so on. You get the idea. This isn't musical at all, but it's a great exercise. Want to really build finger strength? Do it without a pick--using all hammer-ons and pull-offs. Pray for your pinky first, 'cause it'll be crying before you're done.
Hope that helps someone.