Like many of us I wish I could play lead guitar well, it takes a special gift. I mean anyone can rattle around a scale in a given key, but a good lead guitarist like a good rhythm player can make a song memorable.
I agree, get your rhythm playing happening before most else. Playing lead takes talent in my opinion, it's much more than just playing a flurry of notes in quick succession. Its takes a good ear, an understanding of scales, arpeggios and knowing the guitar neck really well. That's just a quick summary.
If you're starting out as a lead player, keep it simple to start, simply emulate the melody in a break, nothing to fancy. Then as you learn your arpeggios and scales, slowly begin to apply them in your playing. My key point is do not try to be flashy when starting out as a lead player. Work hard and practise a lot.
Get to know the fretboard really well, learn the caged system. Learn chord plenty of chord voicings.
Learn and understand how to use arpeggios.
Learn your scales, especially the pentatonic.
Keep your lead playing simple when starting out.
Don't try to be overly flashy, play something that complements the song.