Just a few things from my personal experience.
1) KNEEPADS are a MUST! Don't be shamed into not using them by others- Trust me.
I have the knee pain to verify this

2) Sturdy work boots. I always advise to stay away from those hiking type boots. Go with top of the line leather over the ankle supportive boots. It's real easy to turn your ankle on the job site.

3) Safety Glasses - You only have one set of eyes and they can't be replaced.

4) Lift correctly - How macho is it to pull your back out and spend a week in pain ?

And here's one that most guys don't speak of. Use top quality tools! I refuse to use sub standard tools . They just break and end up costing you money or worse INJURE you.