Winning with humility is harder than losing with dignity. Practice both.

Losing well is hard and it is at least expected, so the character it requires is visible and even admired. Winning well has no such support. Success invites you to become slightly worse, a bit dismissive, a bit convinced you were always going to, and nobody warns you because everyone is congratulating you.

After the next win, go find the person who lost and say something true to them. Keep the routine that got you there rather than relaxing it. Both skills are practiced in the ten minutes right after the result.