This is for all you folks out there who just kicked ass on your interviews.
Congratulations! This letter is not really about how to negotiate your startup package--there's plenty in the aggregator on that. This letter is about all the other stuff you're about to go through--the stuff no one ever prepared you for--as you make what's probably the most important decision you've ever made in your life.
This part is hard. You are about to decide what new part of the country or even the world you're about to move to, and you are likely in your 30s. When you were in your 20s, moving around was easy, an adventure. But now? It's different, and it's scary. You have a life! You like your friends in post-doc land. You have a trivia group. Maybe you have a family or a significant other who you're asking to move with you. You will feel guilt about asking this of them. Talk to them about this.
You may find that when negotiating begins, those nice people at the University who took you out to fancy dinners suddenly aren't so nice anymore. They may try to convince you to take a smaller lab space than the one you were shown, trim your start up list by half, or push back when you ask for personnel funds. When that happens, YOU push back. No one is going to renege their offer because they suddenly think you're a greedy bastard. You know what you need, not them.
You are going to feel more alone in this than you may have ever felt in your life. Maybe your lab mates are also on the market and haven't fared as well, and you feel bad asking them to help you with "problems" they wish they had. Maybe your PI is too busy to help you with your startup list, and your significant other doesn't know a microcentrifuge from a multi-channel pipettor. You will have to think things through for yourself. As scientists, we're conditioned to think in the first-person plural. "We hypothesized that..." "We did RT-PCR to..." For your entire career, you've been part of a team. But right this moment? It is ALL YOU. You are about to be team captain. Say "I." (it feels good!)
You will feel alienated, you will fight with people you love, and you will wonder how this, the actualization of your dreams and culmination of 8-12+ years of training, can cause so much gut-wrenching angst, stress, and even sadness. Take heart, you almost-PIs, and stay strong. You will get through this--personal relationships intact, and with a sweet-ass offer letter in hand. Hang in there.