Yeah, that's kind of a broad question. There are more than a few paths that believe one should never contact demons, and some practices don't believe they even exist. You'd be best off picking one route of study to follow at first and seeing how they deal with contacting demons, then go from there, possibly mixing paths as you go.
Maybe you've already found your path in this, but sometimes they can come to you, without you even knowing who they are in the beginning despite being sort of aware of the gist of this path.
You can try connecting to one and see if you can jive with the energy, its like finding a new friend--or foe-- that you have no previous history with. It's the best thing if they click from the start, but you must suspect the compatibility if there is ever anything amiss or awry from the beginning. Then I wouldn't be as relaxed, because the compatibility won't be as natural.
I don't think you are ready for contacting them, absolutley not!
I'll just say
Invoking and evoking but I really recommend invoking more than evoking since evoking is more summoning without any respect which is a very important thing, respect is the key literally. You don't wanna get on the bad side of the demon.
Take a shower before any invoking/evoking because it's also a sign for respect.
Offer anything the demon likes, I think you're not that foolish to summon a demon you don't know anything about.
Don't have unrealistic thoughts on whats gonna happen when you perform the ritual.
I'd love to answer to any of your questions about demons and summoning if you ever have any wonderings, just mail me.
Well it all depends on your beliefs and whether you want to take a technical approach or a spiritual. Some people use a ouija boards. Some people do summonings. Some people do just normal paranormal investigations. All of these methods work most of the time.