I have only been at the sport a couple of months and I am having trouble getting the nose of my board though the wind when tacking. I am moving my rig back, moving hips and shoulders forward, using feet to push/pull, edging my rails somewhat when going faster and all other tips offered on 'Beginner to Winner'. Coming from slow or planning speed makes no difference. I can only make about 1 in 4 attempts. Seem to get the nose within a few degrees of going though the wind,(not sure of correct term) but then as I move to the other side I get spun the wrong way by the wind as I didn't quite get around far enough around.
eg. I seem to get to 355 degrees when I need to get to 5 degrees. Any extra advice will be appreciated. Thanks.

Are you on a long board or a short board (c 250cm)?

If on a short board do not be discouraged. Tacks are hard. I'm just starting to get back into them since ditching the long board about 2 years ago.

Most people, it seems can't/don't tack anyway. Just gybe. (flamesuit on)

One thing I've noticed:
if you are not planing move to other side after you've gone through eye of the wind,
and vice versa.

Either way you'll be back-winded for a bit (wind coming from the other side of sail).

I usually find when tacking its better to switch around to the new side earlier rather then later and often before the nose of the board has passed through the eye of the wind.

If you are getting spun/backwinded by the sail then what you need to do when you get around the new side of the board, is really tilt the sail forward to help you get leverage to scissor the board the rest of the way around with your feet.

Make sure your footwork is up to scratch too, that was the main thing that I had difficulty with when learning to tack a shortboard. Oh, and keep your eyes on the exit of your tack, looking at your hands/feet just lands you in the water.

Check out Guy Cribb's website, www.guycribb.com/windsurfing_technique_holiday_DVD_0076v01.htm

You will want to read, 'the twist' and 'boomshaka'

I am on a 255cm JP Funride (140 litre)

If you've only been at it for a couple of months then you are doing extremely well!

Tacking is difficult on anything less than 150 litres or so, because it usually involves a short time being backwinded (you're on the downwind side of the sail). Bigger boards let you just grab the uphaul rope, lean the sail, and the board will slowly rotate around to the new tack.

If you're hell bent on being the worlds fastest learner, then practice getting backwinded on the beach and learn how to control the power. Then you won't struggle so much in the middle of the tack.

Don't sweat it, you're doing great