1. Meet in person every quarter. Fly people into the HQ if there is one. If not just rent meeting place.
2. Have a well written handbook like Gitlab that explains how your company works.
3. Onboarding program - remote onboarding sucks. Do onboarding in person (if you can) or assign an onboarding buddy if you can’t.
4. Slack Is Great But (SIGB) - teach people that they don’t need to read everything. Many people get overwhelmed. Great engineers don’t read everything nor should they. Let everyone know that it’s a shared brain or knowledge source - and it’s ok to turn it off to focus.