I have a tall bike and the trainer adds a few inches of height. With the clipless pedals, I feel better stepping up onto something to get on my bike when its on the trainer, I use two milk crates (one on each side).

Keep water, a towel, a phone, and a remote control (you'll need entertainment) close at hand. A fan is extremely useful. I don't move my butt on the seat as much when on a trainer so I have to remind myself to do this from time to time.

I keep old tires to use on my rear wheel when I'm going to put my bike on a trainer as it will use up tread.