Fifteen characters changes the advice
Most username tips assume you have room. On X you don't: 15 characters is the hard limit, and the minimum is 4. A brand name of 12 letters leaves room for one short word at most.
That is why the ideas on this page are shorter than the ones the same keyword produces for Instagram or YouTube. Combinations that would run past 15 are dropped, rather than cut to a fragment like "officialmayaba".
Short handles are easier to mention
People type your handle when they reply to you or mention you in a post, and they see it in every thread you join. A short handle without numbers is easier to remember and to get right the first time.
If your name is taken, try the Clean style with a short suffix (_hq, _co) or a prefix such as "the" or "real". Underscores are the only separator X allows, so use them sparingly: one is readable, three is a typo waiting to happen.