Tip #1: The Long Approach
Many high jumpers, especially those in high school, make the mistake of using a short approach! Within the first three steps of their approach they have already started their curve. Because it is hard to tell how fast you are accelerating and traveling during the curve, this leads to inconsistent jumps and poor performance.
Start your approach about 25 feet behind where you do now. Run perpendicular to the bar and reach a comfortable speed before your begin your curve. This will let you glide through your curve at the perfect speed and focus on your jump, not your speed during your last two steps.
The only reason you may want a shorter approach is if you are a decathlete in order to preserve energy. If you compete only two or three events, you will want to use a long approach. This will help you have greater speed, control, and pop when you arrive at the bar!
Tip #2: Develop a Pre-Jump Ritual
High jumping is like a golf swing, it is important to train your muscles to do the same thing because it can be a tough mental game (especially once the bar gets above your head). One thing that nearly all jumpers overlook is having a pre-jump ritual.
A simply ritual like rocking back on your back foot or doing two skips to start your approach lets your body know you are high jumping again. It can help you get incredible consistent because your muscles will get used to the repetition.
The opposite is true also, if you are stuck in a bad rut, try a new ritual to start your jump, it may be just the change your mind needs to get it out of some bad jumping habits you may have developed. Watch good high jumpers start their jumps, every single one (and I do mean EVERY SINGLE ONE) has a very specific ritual they perform before every jump without fail.