I've negotiated four job offers in the last eight years, two at Microsoft (one joining, one internal transfer that blew up and I left). Sharing what I actually know works vs. what people on the internet think works.
What actually moved my numbers at Microsoft:
A competing offer at a peer company moved everything. I had a Google L5 offer in hand when Microsoft came in with their initial L63 package. I told my recruiter clearly: I have a competing offer from another large tech company, the numbers are $X base and $Y equity, and I prefer Microsoft but I need you to close the gap. They came back with $20k more in RSUs and a higher sign-on within 48 hours. That's it. That's the whole move.
Asking about band range also helped set a ceiling expectation. I asked my recruiter directly: 'What's the top of the L63 band for this role in Redmond?' She gave me a vague answer but the fact that I asked signaled I had done research. My follow-up ask was specific: 'I'd like to be in the top third of band, here's why.' Had more traction than a naked 'give me more' ask.
What did NOT move anything:
Cost of living arguments. Didn't land. Recruiter was polite but this is baked in already.
Highlighting my qualifications. Completely irrelevant at the negotiation stage. They already decided they want you, listing your resume points again doesn't move comp.
Asking for a higher base and not equity. Microsoft recruiters consistently push toward equity flexibility over base movement. Base is tighter. If you want more total comp, focus your ask on RSUs and sign-on.
The sign-on: Microsoft uses the sign-on to bridge the gap when base and RSU bands are maxed. I've seen sign-on amounts vary quite a bit ($20k-$120k at different levels) and it's often the easiest lever. The downside is year-2 cash drops once it stops. Ask if it's split over two years or one, and model your year-2 carefully.
One thing that surprised me: They moved faster than I expected once I had a real counter. 48 hours. No 'let me check with the hiring manager' delays. Felt like the recruiter had authority to move within a range without escalating.
Good luck to people in the middle of this. It's stressful but there's room to negotiate.