Try not to constantly readjust, be deliberate about your grabs and movements
Body position: flagging. When you reach up and right, balance by putting your left foot down and left. Basically you want to be stretched out to keep balanced
Grip
Don't grip too tight. Only use as much pressure as you need.
Footwork
Use your toes, not the middle of your feet
When the toehold seems tenuous, you should counterintuitively add your weight to it. This will increase friction and make the toehold more secure
Put your toes right into the wall. It helps to start your toes above the toehold and then come down onto the hold