Your boat tacks pretty quickly, so good timing comes down to fractions of seconds. Single-handing, being completely consistent will always be an elusive goal, as the tiniest misstep will throw it off. (By contrast, in my boat, I start my turn, take a nap, wake up, look around, make tea, come back up, and think about sheeting in the leeward sheet.)
Pretty hard to diagnose your tack exactly, but I will tell you what I have seen as an instructor, as the most common "mistakes". (I put "mistakes" in quotes because they aren't really mistake, per se, just areas that could be done more effectively.) In no certain order:
- Letting the original leeward sheet out too soon. This is pretty much the most common problem I see, especially for single-handers. Since you have a few things to do in short order, it is tempting to let out the sheet before it is completely unloaded. It sounds like you've got this figured out.
- Sheeting in the new sheet too hard too fast. To make the best windward progress, you do actually want to overshoot slightly and then turn up and sheet in as you build speed. If your goal is simply to point as high as possible at all times, do as Stu says and sail from close-hauled to close-hauled, but that is not actually the best way to make windward progress. Actually, 90 degrees is about right, as a starting point. Your boat will be a little narrower than this (like maybe 75-80), whereas mine is more like 100 or so. I'm not sure where Stu is coming from that this is "nuts". It is a really good way to ground your turns for consistency - to steer relative to that 90-degree landmark. This touches on the next issue ...
- Sailing too high. Your boat will probably make the best VMG about 40 degrees off the wind (I am guessing - I don't really know your boat that well). Your boat will sail higher, but that won't necessarily get you to your destination any faster. GPS is really useful for figuring out optimal angles, but understand these will vary a bit with conditions. After a while, you can feel the angle of diminishing returns - that angle at which you are pointing higher but speed-over-water drops off palpably. Just below that is where most boats make the best VMG (as a close-enough rule).
- Fussing with the traveler too early. Your traveler angle does matter, but it should not take precedence over sheeting. Ideally you would move your traveler as you built up speed, sheeting in the headsail, and pointed up. But, you can't do all three simultaneously and you get more benefit from a properly sheeted headsail.
- Abrupt rudder deflection. The turn should be smooth and powered as late as possible on the original tack and as early as possible on the new tack. People get rushed to get it all done and sometimes push the tiller too hard over, all at once. This just causes the rudder to stall and is just like putting the brakes on. Similarly, when overshooting, people will sometimes overcorrect and stall the rudder the other direction. Smooth and steady. The only time you want to steepen the rudder angle is right after you loose the original jib sheet. Your SOW will have slowed, making the rudder less prone to stalling, and you need to get that bow across the wind as quickly as possible. (If seas are rough, you might need to make your turn a little quicker because the boat slows more rapidly. Timing the start of your turn between waves can help on a smaller, more responsive boat.)
Bottom line: Understand that the best back actually has a slight "S" shape. The goal is not to get from close-hauled tack to close-hauled tack as quickly as you can, but to maintain as much of your original speed-over-water as possible (i.e. avoid losing speed-over-water). If you have a passenger and want to refine your technique, have them watch your SOW and call it out. That will give you feedback as to what is working and what isn't, to maintain speed.
The lighter the air, the more you need to overshoot, but use 5 degrees as a starting point for "about" the right amount. The lighter the boat, the less you need to overshoot ("light" meaning "relative to sail area").
but I still find my tacks to be inconsistent at best. always single handed, even with a passenger onboard, but my general process is: locate a spot 90* as a target, release and hold the working sheet, swing rudder, allow the jib to back fill and push the bow through the tack, release the now lazy sheet as I pull and set the new working sheet and simultaneously center the rudder. sometimes I nail it, sometimes I over or undershoot. 
