I guess this still applies to your point number 1, but I'll say it anyway: Avoid small B2B companies that have one or two big customers among a bunch of smaller

I guess this still applies to your point number 1, but I'll say it anyway: Avoid small B2B companies that have one or two big customers among a bunch of smaller ones. These big customers know they have leverage over the company and will make it do whatever they want, and then change their mind completely 3 months later, at the expense of your sanity. You could ask during interviews "how many customers do you have? are they big?" and usually the company tries to brag that they have that one big brand name, but in my experience this is a red flag. Be careful.