Hi Murph,
You've got some tremendous joy coming when you do finally crack the footstraps. I had to have a lesson before I figured it out, hopefully you're not as dense as I was back then...
The biggest problem for beginners with going for the footstraps is luffing up into the wind. Basically you plonk the front foot into the strap, which is well outboard of where your front foot normally is, put weight on it and suddenly the board turns into the wind and you fall off. The secret is to push down with your toes (both feet), and visualise keeping the board flat.
To actually get to the straps requires a modification of technique as well. Up until now you've probably been sailing on a beam reach (directly at 90 degrees to the wind) most of the time. To get to the straps requires you to head downwind, and sheet in. This puts you deep into catapult territory, which makes sense because you want to get weight off your feet to put them into the straps! It also gets you planing. If you've only used the harness a handful of times I don't think you're quite ready for the footstraps, but no harm in trying.
Have you gotten planing yet? It only makes sense to go for the straps when you're comfortable steering with your feet while planing.
quote:
I can still remember the feeling of shear terror the first time I got on the plane. I felt like I was going a zillion miles an hour with no steering.

I told anyone who'd listen that night about how the "Swell was frozen solid!"