Instead of focusing on changing your words, could you try to overhaul your thought process?
What I mean is this: I looked at it as DS had a legitimate desire to do something, to explore, to learn. So my goal was to find a related activity that would satisfy his impulses, and not simply to get him to stop what he was doing. kwim?
So if he was banging a block on the window, I'd try to give him another outlet that IS ok to do- wipe the window with a cloth, bang on the floor with the block, or build with the blocks, etc. This gives them a method of controlling impulses in the future (instead of just stopping), let's them know that you're on their side (and you want them to be able to do it, just in a socially acceptable way), and is far less frustrating for them (because they still get to satisfy their impulse).
I don't necessarily avoid saying "no" or "don't." I just always try to give an alternative that satisfies the original impulse.
Maybe if you look at it that way, then your language will naturally become more positive.
Becky, partner to Teague, SAHM to Keagan (7yo), Jonah (2yo)