Get booked on a skills course if you want to learn properly. Best money you can spend if you are serious about riding well.
I did Neil D’s jumps and drops this summer and whilst I wouldn’t say I am going to be entering Red Bull Rampage anytime soon, I now have the confidence and (admittedly not perfect) technique to hit jumps and drops that only a few months ago I wouldn’t have done.
If you don’t have the cash or desire to go on a course, take it back to basics… Learn to manual – properly.
Then practice off kerbs/lips/drops.
Then learn to pump – properly.
Then practice pumping your way round a pump track, twice, thrice, without pedaling.
Then learn to bunny hop using these skills.
Then – and only then – practice, and practice, using your pump/bunny hop to get over a tabletop or small jump. You shouldn’t need hardly any speed to clear one. Pump the transition (upslope) and bunny hop over the tabletop.
Once you’ve practiced and practiced this, go bigger, go higher and go gappier. The only variable should be your speed depending on how big the object is you want to clear – your technique will remain the same.
As I say though, get booked on a course – it’s not the only way, but it’s the best way.