Welcome back, Phobetor! Glad you've decided to return and feel free to let us all how we can help

As prog4p4rv18 mentioned, try avoiding those negative thoughts. I know it's much easier said than done, but if you find those negative thoughts creeping into your mind, stop them as soon as you can. If you think someone horrible or ugly is going to appear, say, "No! Someone lovely is going to be here!" or something along those lines. You can also try switching your actions to something else. Instead of going forth into a potential "nightmare" turn around and head in another direction. Start doing something else.

You could also try making a plan as to what you hope to accomplish. While you're awake, decide what you want to do. Plan for it to succeed! Remind yourself what your intentions are and when you next become lucid, act on that plan rather than waiting around for something bad to happen. Act! Enjoy your dreams. It may just take practice, but in time you'll figure it out.

See you around! Sweet lucid dreams.
-Amé