I wouldn't recommend using dream signs, especially if you only RC when you see one. That way, you only have a chance at becoming lucid when you see a dream sign, which won't be in all your dreams. This greatly cuts your chances of having a lucid. Dreams can look extremely similar to real life, and you usually don't question things when you're in a dream. If you aren't already, along with your reality checks, question how you got to where you are, and stuff like that. Work on awareness, both external (checking your surroundings out) and internal (listen to your heartbeat, note what position you're sitting in, etcetera).

The more skeptical you are, the better. Once you have a few lucids you'll see how much skepticism in real life helps. Good luck!