I can't become lucid?

Yes, it would be a good idea. Sorry about the short reply, I somehow expected you to know it. Forgive me and best of luck.

Set of techniques I usually recommend to newbies:

I always like to recommend MILD, VILD and WBTB.

Recommended Long Read:
Big VILD topic.
MILD Tutorial
Big WBTB Topic

Short Read:
VILD is mostly about imagining the dream setting you would get lucid. Usually by creating a context you would RC.

MILD is about repeating phrases that you want to stick to your mind, so you would probably recall it during the dream, possibly to RC or to be motivated enough.

WBTB is about waking up and getting back to back. Some people fall asleep faster when getting back to bed in the middle of sleep, which helps you to get into a dream much easier than initial bedtime.

Also, the techniques are not 100% fool proof. You cannot expect them to work at first attempt, sorry, but it’s true. You should insist on them. Patience is golden here…

Another technique that could work for your specific context:
Since you claim that your crush is your DS, something that could work for you is CALD - Character Assisted Lucid Dreaming:

Basically, you could imagine your crush (or some other recurrent person in your dreams) as someone that would remind you to RC. Imagine it hard so it would be incubated into your mind, and hopefully, then carried to your dream.