Top tips for landing large B2B contracts?

Working on a few big pitches for clients that could evolve into long term contracts.

We basically offer a bunch of standalone products and services, and are now putting it together in packages to offer as a year long contract or more.

What are the most important factors to keep in mind while negotiating such contracts? What kind of research should I do on the clients? Any words of advice on the approach with current and future prospects?

Context: We have a decent brand value (b2b2c) that brings inbound leads every year, and we've mostly just been busy with them so far. We are just starting outbound properly, but don't want to dilute our brand value.