-Work on your recall. More dreams recalled =more chances to lucid dream. Noticing your natural awakenings at night helps with this.
-Nose pinch is a good RC.
-Repeat your mantra as many times as possible. Don't focus on falling asleep, focus on your mantra. Recalling your mantra while you're dreaming starts the process of becoming lucid.
-As far as staying optimistic, do you have anything better to do at night while you're sleeping? LDing a fun mind game, whether you succeed or not.
-Focus on what you're going to dream while you're meditating.