getting faster at the 3x3

we dont have any "pros" here (gets ready for one of james' jokes), but i figured we still need one of these threads (if you think we need one for 2x2, 4x4, 5x5 etc, do it).
i figured it could run this way:
1. person posts a question
2. multiple people help/answer, not just one person
this way you get multiple opinions, and that leads to better advice

ill start:
when i was using the beginner's method, it told me to do cross on U, and that habit has stuck, any tips on going to cross on D

Being that I'm the worst cuber on these forums, it's a good thing that there is a step 2 to your thread. However, as long as you know what to do as you inspect your cube ahead of time, you can make the cross on the Down side without even looking. I don't know if I'm being too obvious or not, but sorry if I am. I tend to do that a lot.

it sounds easy in theory, but habits are hard to break