Scales are great for more advanced soloing, but I would start with a catchy riff like the lead from Smoke on the Water and work from there. If you have the music background for it, you could flesh out a basic chord progression to go with (or take one from a song you know), but you don't really need to. Just get the basic riff down, enter session mode, and play the main riff a few times to let the band know what you're doing. You'll know when they've got it down. Then try a variation on the riff, repeat the original version, try another variation and so on. Just keep referring back to the main riff on a regular basis so the band doesn't get lost. My typical settings are - Root: E A or D, Mode: Pentatonic Maj or min, Complexity: jam, Tempo: 90 bpm, Groove: pushed, Slew: on, Room: club. I'm not a great guitar/bass player by any means, but this gives me the freedom to noodle around a bit with enough structure to make it productive/decent sounding. When you get comfortable doing this, it's even more fun playing with a friend, trading the lead between two guitars or guitar/bass. I've had some great sessions where we've worked up entire songs starting with just a lead riff and basic chord progression. I just wish RS would let you record and export your sessions. That's my suggestion. Maybe some others will chime in. Good luck with it and let us know how it goes.