Take all endorsements you're allowed to. If you live in Arkansas, take the Hazmat test too. Study for them, don't go in cold.
Practice as much backing as they'll allow you. Same goes for Pre-trip Inspection.
Realize this profession is very saturated, so try to find what you want out of it and go after it. Separate the BS from the truth as best you can. Don't be a hard ###, but stand your ground.