Good work on remembering that one dream. Even if you only recall one part of it, it is important. If you keep a dream diary, the more you recall the better it gets. Tonight you will remember more, then more the next night etc. Good recall is quite an important skill when you are trying to lucid dream, using the DILD technique. If you don't know what to expect in your dreams, then how do you know when to do a reality check? Or at least that is what I think, but everyone is different. It's OK if mantras don't seem to work for you. I don't seem to get much use out of them, either. You just need to experiment with different techniques until you find the one that suits you.