If you did it as a kid, you can certainly do it now. To use the cliche, it's like riding a bicycle; it may take a few tries, but you never forget how. You are doing all the right things: writing in a journal, thinking about it during the day, etc.
Set your alarm clock for the early morning hours (3am or so?), then wake up, turn the light on, and read an engaging book or magazine for a half hour, then go back to sleep. This is the BEST way to maximize your chances of having a lucid dream. I think that by going from sleeping to waking to sleeping again, it confuses the brain as to whether it's awake or asleep, and makes a lucid dream MUCH more likely. If it doesn't work the first time, try it again and again.
Yes hon, you NEED to buy LaBerge's book. Without that book - even though I had many lucid dreams before reading it - I wouldn't be HALF the lucid dreamer that I am now. No lie.