Tip 09: Be nice and give your seat up if its needed
Again, this should be obvious. It's the same tip as you get taught from day one on buses.
If you have a seat and someone else needs it more, give it up for them. Let them sit down. It's just common (or un-common in most cases) courtesy.
This is worth doing if for no other reason than just another chance to tick that "good deed" box again.