Thanks for the rec Hilary! I just ordered a copy of Dream Gates. I could definitely stand to practice visualization more before bed-- unfortunately I tend to get very unfocused right before bed and my mind wanders to all kinds of waking life concerns. So it's gotten harder to maintain that singlemindedness before falling asleep, compared to when I was a kid. I think my life was just less mentally demanding back then.

@DarkestDarkness -- Thanks for the response, you've given me a lot to think about. You picked up on my perfectionism pretty quick, which has always been a factor in my lucid dreaming over the years. It's hard for me not to berate myself for my failures, which leads to a lack of persistence, which leads to more berating myself over lack of discipline. It's quite easy to sour the experience.

Your point about thresholds and doorways is a really good one, I'd like to work with that... if you were trying to manifest something behind a doorway, how would you do it generally? Do you think to yourself verbally, "I'm going to open that door and see a [BLANK] on the other side," or do you engage in some sort of visualization from within the dream? Is it sort of a "knowing," like you just tell yourself that you know your desired dream object is behind the door?