1. On Day 1, read the faculty manual/handbook. Read it and know it as if it's your JMP. It will come to rule your life. Read it. Read it. Read it.
2. Shut up. In your first year, barely open your mouth at faculty meetings. Speak when spoken to. Intuit the internal political conflicts that bubble under the surface in your Department, and avoid them.
3. Your Dean is more important than anyone in your Department.
4. You will know this already because you have read the faculty handbook, but you are going to be evaluated sooner than you think. Forget about the tenure decision, you've got a mid-term review in 3 years and you might be fired. It happens and nobody speaks about it. You get a free hit the first year but by year 2 you better have something.
At my private university, evaluations are cloak and dagger. I can request to read the letter from my Department to my Dean but I cannot appeal it. Things are more transparent at other institutions. The points of conflict will be outlined in the handbook. That's why you read the handbook, and why you realize everything goes through the Dean.
5. The principal advantage of being "the guy known for X", as opposed to "I have written four papers that barely overlap", is increasing returns to scale. If you're that guy on X, you are asked to discuss papers at a conference on X. You are asked to referee on X. You're asked to organize the field conference session on X and so on. Ultimately this means Larry Katz or Raj Chetty will one day ask for your opinion about X, and then you're okay on X. None of this happens if you're not consolidating your work.
6. Everything is political. Just keep your head down and do your thing for six years. Don't complain about the mandatory training on diversity initiatives. Don't badmouth your Dean at the bar, because his neighbor might be next to you (this happened to my friend).
7. Three-ish times a year, apply for small grants and fellowships. Spend two days working on a proposal to get $3k in outside funding for some project. The project should be important enough to do anyway so this is all infra-marginal. However, evidence of consistently receiving awards/grants looks very good on a CV compared to the difficulty of obtaining a relatively meager $3k.
-- Bro who struggled in his first few years, but just accepted an outside offer with tenure.