Learn Lead Guitar
The lead guitar parts of a song are often the most expressive parts a guitarist can play.
On top of that there are all sorts of techniques and tricks that can really draw attention to the lead guitarist. There are some little things to keep in mind in order to become a much better lead guitarist.
Learn Lead Guitar Timing
While guitarists generally are stereotyped as having a poor sense of timing, of all instrumentalists, lead guitarists are notorious for it.
Timing is important for all musicians. If anything, a lead guitarist should have a better sense of timing that many other instrumentalists, not a worse one. Lots of lead parts have weird timing, lots of syncopation, lots of different intervals in the same bar, and all manners of odd things that making playing in time more difficult.
This applies to improvisation as well. While it might seem like an improvising guitarist could hit notes whenever they want, in order for it to sound really good, they really do need to play in time. An improvising guitarist should have their sense of timing so firmly ingrained that it is no longer a conscious factor. This takes a heck of a lot of practice, but the end results are worth it.
Some good information here on lead guitarists and their responsibilities. Now, if we could only do something about their egos. haha