Katy,
Not much of a "legendary jumper" but my tips are as follows:
Chop Hop/small jump:
Look forward and find a piece of chop with a sharp face or one coming at a slightly sharper angle. (I am aloways looking 20-50 meters ahead for the right piece of chop) You need to find something that you will hit close to a crest (just before (say 90% of the crest) is usually OK and sometimes better as you get less lift and more control - good for beginners) If it is breaking you are probably in the wrong spot - I like to be about 1-2 metres up wind of the breaking part of the wave/chop.
At full speed, As you move up the chop push down on the back foot to bring the board up into the wind and sharpen the angle of attack on the chop - sheet in a little (you can stay in the harness ropes). - as you hit the lip of the wave/chop lift slightly with your front foot and "voila' - you are in the air.
As a beginner I would advocate being out of the harness ropes - this usually means less catapaults as you land. The bigger the wave/ jump the less likely I am to be in the harness ropes.
The trick now is to stay in control and land well.
Drag that back foot in behind you (and up) and let the board drift/sail down wind (sheet out but keep pressure on the sail to maintain power) to get max fly on the jump . Try to land soft - I'm no expert in this area but I aim to land the board around the mast track or just behind with some forward motion. If you come straight down (vertical flat you will know about it). Once you have landed sheet in to put the power down again.
Try to be gentle on the back leg when you land to avoid 'railing up' into the wind and stalling.(Don't sheet in too hard) If you are not careful here you can also suffer spin out. Sail down wind - get back on the plane and off you go.
Best tip: go and watch some folks doing it. Ask the locals: - Every one will have some slightly different tips.
FYI. It is possible to jump 12 foot boards - so most of the modern equipment will get airborne if you know how.
You will have plenty of stacks and catapaults

and spin outs; you will land the board flat and plant the nose - this is a 'normal' experience- keep trying.
When you nail the first jump and sail off you will be hooked!!

-J