What are some employee recognition best practices for startups?

Bravo (https://getbravo.io/) can serve this purpose effectively. You can give your colleagues Bravos (recognition points) as an appreciation that one can redeem later for rewards. Moreover, you can celebrate birthdays, work anniversaries, or other achievements which keep your team engaged in the workplace.

My practice is just to make them feel they belong here and always have an open communication with them about their importance of their role.

Just give them a bonus or raise. It not only makes them feel valued but also helps improve their personal life, so they'll work harder to give back to you. This triumphs everything else.

Of the many things we did, one that was much appreciated was a day set aside for employees to present their achievements before the others. How they built a tricky feature How the test script for a tricky feature was done How a particularly hard customer ticket was handled, etc. Each person presenting got about 7 min on stage followed by Q&A with some rules No criticism, but suggestions and appreciation welcome Informally, seniors were encouraged to appreciate juniors from other divisions