Anchor yourself in the dream before you do anything. Rub your hands, feel the wall or do some exercise. You need to activate your senses so your mind doesn’t begin to focus on your real body. Constantly remind yourself that you are dreaming, and do active RC’s, like plugging your nose and trying to breathe as much as possible. If you do begin to lose the dream, start spinning around or fall backwards.
Also, you should check out this article: Prolonging Lucid Dreams by Sandra. She gives some really good advice! Best of luck to you 
Edit: oh, and welcome to LD4all 