I just spent some time putting together a short list of tips about this topic for another member (HelloBro123) I'm copy/pasting it here, it would be better that in my introduction thread XD I have four reccuring DCs, in this I'm talking about one that I wanted to meet again after seeing him once, but there are things that hold true for all four of them and things that can be adapted.

- Don't give up. took me almost a year to have him where I wanted him (granted, I flailed blindly a lot and was new to that lucid dreaming thingy.)
- Document each attempt; write down everything about it. Everything. Everything you've seen, felt, smelled, even tasted. re-read it from time to time.
- Try to think about your DC during the day. Just a thought in passing should be enough to increase the possibility of them to be in your dreams too.
- On the same note, give them a name/find out their name. It should help giving them some consistance and stand up from your other DC.
- Find out in what situation you first met them. Try to recreate it and expect them to come back!
- Find a summoning method that work for you. I have three: calling their name (usually work when I see a lot of people but don't try to see their faces before calling) asking another DC where I can find them (their can throw you in a wild goose chase tho.) and my favorite: I put my hand behind me expecting someone to pick it up. (It can have surprising results, but it's a dream after all.)
- Keep summoning them. They don't look like last time? Tell them. They sound different? Tell them too. They should become more and more consistent over time (mine flat out told me that he was working on looking and behaving the same way on all my dreams!)
-Allow yourself some breathing room. Their may be very slighty different in each dream, but as long as their core caracteristics are here, it's fine. If their start to deviate too much for you, point it out to them, there may be a reason for it!

A lot of it boil down to dream belief, but that's a perfectly usable tool, in my opinion. My subconscious can and will be pretty facetious, but if I'm convinced of something, it is pretty willing to play along.