I use Lexol as well. It smells like a saddle shop inside afterward. Really nice in my opinion.
It's a three-step process.
1) Vacuum the seats well. You don't want to be abrading any dirt that's there into the leather.
2) Use Lexol's leather cleaner. This does a good job of removing skin oils and other contaminants from the leather surface.
3) Use Lexol's leather conditioner. There's a temptation to use a lot, but it takes just a very little amount. After the conditioner sits for an hour or two, go back with a clean and dry cloth and buff it off. Even new leather just feels better to me after a good treatment of that stuff. But again, don't use too much. If you do, or if you don't buff it all out, the seats just feel sticky or slimy. A little goes a long way.
Done right, you'll never use anything else (assuming you like the smell, that is). I do this once a season to both cars.