My pre-boarding habits are very odd, or at least unusual. This is what I do:
1. Have my boarding pass in my hand, in case the cabin crew want to see it.
2. Check what seat I am in (if on an allocated-seat flight) or know roughly where I want to sit (if not)
3. Have my reading material and other bits and pieces already extracted from my carry-on bag
4. Have my carry-on bag ready to stow
Once I get on, my behaviour becomes even more eccentric:
1. I move as quickly as possible to my seat, being careful not to club anyone with my bag.
2. In one swift movement, I stow my bag in the overhead locker, sit down, and get out of the way.
Yes, I know, I'm a weirdo. I wish I could faff about, fishing for my boarding pass, wandering aimlessly looking for my seat, blocking the aisle while I slowly unpack my newspaper, cardigan, sandwiches, etc, from my bag, like the rest of you. But I just can't do it.