After cleaning the yoyo and lubing it, tighten the halves together. Not TOO tight, but enough to keep it together during play. Next, throw the yoyo and feel for vibration. Tighten JUST A LITTLE BIT. Throw the yoyo and feel for vibration. Tighten JUST A LITTLE BIT. Repeat this until your yoyo is playing smoothly and wonderfully. Remember, the tightening is done is tiny amounts.
That is how I learned to tune my yoyos.