My warnings:
Don't pop your bearing shields, unless you actually plan on cleaning them somewhat regularly. In fact, we all should probably clean our bearings more often, regardless, but that's a different topic.
Don't try to skate something slightly out of your comfort zone/skill level with gear you aren't comfortable in/broken in yet. Brand new shoes, new bushings, etc. unless you know how they will operate as new and are ready for it.
Don't by graphic grip unless you know you'll enjoy looking down at it every session.
Don't use Allen hardware, as most people don't have an Allen key when on a session if you need to tighten a screw but they likely have a Phillips screw driver. That is, unless you plan to have an Allen key with you all the time.
Don't buy Bronsons. They're not worth the marketing/price. They are average at best, if even that.
Krux trucks. Just no, like Off said.
When gripping a board and doing lines/cut outs, etc. think about where you do all your tricks and where you NEED grip under your feet. This is important!
Don't compare your skating to someone else's, even if you have a similar amount of time skating as them. Instead, look to your fellow skaters as inspiration to learn from them. Maybe they have something you don't, but you may also have something they don't, so sharing/learning from each other is a better outlook!
🙂