Start with your own brand terms. Your company name, product name, common misspellings, and abbreviations all need reservation. If your company is "Acme Corp" operating "Acme Platform," reserve acme, acmecorp, acmeplatform, acmeapp, acme_official, and variations. Bots will register these within hours of launch if you do not.
Next, block the universal system terms that every platform reserves. This includes admin, administrator, root, system, api, support, help, contact, null, undefined, localhost, and similar. These form the baseline that no platform should skip. Use a pre-built list rather than creating one from scratch.
Add your platform-specific terms. If you have features like "Spaces" or "Stories," reserve those words. If your app uses terminology like "creator" or "merchant," block those too. Think about every noun in your product that users might try to register as a username.
Finally, consider future terms. AI, crypto, NFT, metaverse — these words seemed niche a few years ago and became premium handles. Reserve general technology and industry terms that might become valuable. You can always un-reserve them later, but you cannot reclaim handles that users already registered.