The condition and setting up of the sails will also have a great bearing on pointing ability. There is a very good book on sail trim called "New Book of Sail Trim" edited by Ken Texter. Boat Books in Westhaven have this in stock @ $48.95 and the ISBN Number is: 0713644264- 5. This is no doubt available from other good book shops as well. Boat books phone number is (09) 3585691.1 would recommend getting your hands on a copy.
The H28 responds well to subtle changes in the positioning of the genoa cars and the tension on the halyards of the main and genoa. Also the backstay tension will affect the on wind performance and we find on our boat to obtain best upwind speed in 12knots or less we have very little backstay applied. Over this we need to apply more tension.
Fit tell tails (wools) to your genoa and mainsail on both sides. (Available from your sail maker or chandlery in made up packs).
The over sheeting of the headsail will also cause the main to stall and back wind up the luff due to the slot between the main and headsail being closed up. The rule of thumb here is; if in doubt let it out!
The amount of kicking strap applied will control the twist in the leach of the main and this will also influence the amount of weather helm and pointing, as will the position of the mainsheet traveler, which you should be able to pull up past the boats centre line and to windward. This pulls the boom on to the centerline of the boat without flattening all the shape out of the mainsail and effectively opens the slot between the sails that I mentioned above.
All of these points and more are fully covered in the book I have mentioned. Quite often your sails will only need re-cutting which is much cheaper than a new suite. I have mentioned some of the main areas and it is really only through experimenting with settings on your own boat that will get peak performance when sailing.