1. You stack the glasses and plates
Your intentions are obviously good and you're just trying to help consolidate your mess, however, you probably don't know the correct way to stack them which can lead to some broken glass and an angry waiting staff.
If you do decide to stack, go for the plates instead of the glasses and make sure that the biggest plates end up on the bottom.
2. You sit down at an uncleared table
Technically there is no bad reason for you to sit at an uncleared table except the server is going to feel obligated to stop whatever they are doing just to make sure you aren't sitting at a messy table.
3. Not mentioning that you will be splitting the bill
Okay EVERYONE is guilty of this at one point or another.
If you know that you will be splitting the bill ahead of time then you really should let your server know asap.
It's a lot harder on the server to divvy it all up at the end, especially if you and your friends are a couple bottles of wine deep and not sure who is paying for what.
4. When you're being way too chatty
of course you want to be polite and develop a friendly rapport with your server, but if you take too long to tell a joke or boring story, then you are severely restricting them from doing their job and serving other people in the restaurant.