First, always remember that speed going into your jibe is your very best friend.
If you have lots of speed when you begin your carve, that carries all the way through and it's what will keep you planing on the way out.
In order to work on your fully planing jibes, it's probably a good idea to break it down into at least 3 or 4 "stages" and work on each stage individually.
At first, concentrate on making wide radius jibes that help to keep your speed up, and give you a bit more time to get your timing right.
"Timing" is the real key to making nice jibes.
If you have speed and timing, everythig works and you may find yourself with your sail flipped, your feet switched, and still planing, or at least only a pump away from plaing out.
Work first on making your transition from sailing straight into the entry of your jibe smooth and in a manner that maintains your speed.
If you are super powered up, then oversheeting (like all the jibe guru's suggest) works well, but if you are sailing in more real world conditions where you either don't have alot of excess speed going in, or you aren't really powered up fully, then you need to keep a little power in your rig all the way until you flip the sail.
Learn to use landmarks, bouys, etc, so you know where "downwind" really is.
Then flip a little early. Flipping your sail can be boom/mast/boom or boom to boom when you get a little better.
Flipping a little early is better as you have a better chance to get your rig powered up after the sail flip.
Footwork and timing will allow you to set your rail on entry, carve the board around to nearly downwind, flip your rig, maintain the carve angle as you shift your feet, and finally power up the rig while still heading well below a beam reach.
That's the basics, now you need to go out, work on each stage, then begin to "put the stages together" and do alot of jibes.
Every time you blow one, stop a moment and think about what you did vs what you think you needed to do. If some part of your jibe isn't working, doing it repetitively without making any changes will give you repetitive failures.
Work on the timing most of all.
Once you get the timing right, it becomes much easier to "fix" individual stages of your jibe because you will be able to maintain your speed fat better.
Hope this helps,