I'm going to be a pain in the arse now. I don't like the phrase 'lead guitar' and I don't think there should be such a thing as a lead or rhythm guitarist. The guitar in pop music is primarily part of the rhythm section. Having said that, it has lots of scope and possibility, and should be explored as fully as the guitarist wants to.
But to my mind the best guitarists are the ones who do both together. People like Johnny Marr, Jeff Buckley, that guy from Muse, the list goes on. Sure, some of them may be able to kick out an over-the-top guitar solo, but to me that's secondary. As a songwriter, the songs have always come first for me, which means finding the guitar part that best suits the song, even if that guitar part is a 3-note repeated arpeggio.
Peter has good advice; learn the guitar parts that turn you on, learn them so well that you understand what makes them tick. Once you understand it, you'll start doing it naturally. There's no secrets, no tricks, just good old-fashioned practice. Lots of practice.
Have fun with it