What a super helpful post - I've just been trying to do this recently and I was doing exactly what you said not to do - lol
I think I just manifested this post...
Also, David, in reply to your post above, I also have a lot of trouble clearing my mind (especially from those nagging to do lists), but I have found that the less I worry about it, the easier it is to achieve. Anytime I have a stray thought, I simply acknowledge it as a thought as soon as I'm aware I've done it, and then move on. I've found this helps to become more aware of the present moment. Also, not getting frustrated is key, because then you simply admit you had a stray thought and then go back to your mantra, or whatever you may be using to help you meditate. It takes me a LONG time sometimes before the stray thoughts settle down - 30 to 45 minutes sometimes... I have a very active mind though (too much I'm afraid...)
The time of day is important for me too - I seem to do better late at night for some reason.
Sorry if I'm rambling