From my experience, I stated to myself that I won't do any summoning ritual, I'll just use conjuration service. EXCEPT, I'm able to see and communicating with the spirit. Well if we're talking about summoning ritual such as letter method, or the one that Erik Von Roth provided, there's no guarantee that what might come is the succubus, there's a chance it might other spirit or demon masqerading as succubus. Other method that give conviction is black mirror, which is very dangerous and can be startling because you can see the succubus, even in their true form. You also need to watch Lilith's behavior as you're contact her directly, becareful to not upset her. I agree, CH method is safest.
Because of those reasons, I choose conjuration service because I like play safe, and can't deal with uncertainty, they're stress me out.
I think those touches are from the succubus that drawn to you. I've experienced that kind of thing first time I summoned a succubus (not exactly succubus, she was a female spirit that has similiarity with the succubus). It began when I really eager to have succubus, then starts stating what I want to Lilith. When I'm about to sleep, I felt a cold temperature, and something touching one of my feet. As the time goes, the touches feels stronger. Just tips though, don't get scared of them, or they might try to scare you, in my case, I starts to see clear manifestation and heard breathe, not only besause I'm scared, but I also did something that upset her. I honestly felt haunted for a month or more. If you still want to do it, you need to have a clear mindset. Also, I can say, being a bit indifferent, especially about morality can help you.
"Whoever keeps his mouth and his tongue keeps himself out of trouble."Companion : U a succubi