Learn to adjust the height and length of the Ws Numbers List strings, this will need doing if you've never done it or if you have changed the gauge Ws Numbers List of strings that you use. If the action is wrong due to a curved neck (or a flat Ws Numbers List neck) you'll have to adjust the truss rod. look it up! To set the intonation (length of each string) use your tuner to compare the 12th fret with the open string.
SHARPER than the open string or Ws Numbers List harmonic, adjust the screw at the end of the bridge so the section of the string that vibrates Ws Numbers List is made LONGER. If the 12th fret is FLAT compared to the open string, you need to Ws Numbers List SHORTEN the string length. If the knobs are wobbly on your guitar, fix them before they get any worse. Check the side of the knob to see.
If there's a tiny screw or Allen bolt Ws Numbers List to loosen. If not, just pull the knob straight off (like on a strat for example). You'll see a Ws Numbers List hexagonal ring that you should tighten. Try to not let the stem of the pot turn, as it could Ws Numbers List strip wires inside. If the output jack is dodgy (it's not an INPUT jack, it's an OUTPUT jack!!), tighten the hexagonal ring around it. Try to not let the stem of the jack output turn.