To tighten, loosen the opposite spoke until it is snug and then check if there's any play in the rim by gently pushing on it with your hand. If so, adjust as needed. When finished tightening all spokes evenly (one at a time), use two hands to turn over the wheel while holding onto an end of one side of the axle - this will help you align and tensions spokes correctly across both sides of each other simultaneously. Then, turn back around 180 degrees, checking that they are still tight before releasing your grip on them.