1. 'Wide bow' shape. A boat that is maximum width at the foreward measurement stations will be more bouyant and tends to plane earlier and go through waves better. Go for a fair curve with the foreward measurement stations at maximum width and approaching maximum legal hull width about 6 - 8 inches aft of the chainplates.
2. Flat Rocker. A boat that is at the maximum flat rocker measurements on the aft planing sections of the hull will tend to plane earlier.
3. Length. Having the bottom panel at minimum length and the overall length of the boat at a maximum will give the best angle to the bow transom for going through/over choppy waves.
4. Gunwale width. The gunwales should be maximum width along the cockpit - this will put the crew a few mm further out when trapezing, giving slightly more righting power. The gunwales should have a good non-slip finish in that area (sugar in the clearcoat works well). To save weight the gunwales can be narrower fore and aft of the cockpit, but don't shave them so narrow that it becomes difficult to pick the boat up.
5. Side deck angle. Have the side decks as flat as possible - this is accomplished by having the height of the tank sides as low as permissible. While not exactly a speed secret, having flat side decks will make it easier to sail the boat flat (you feel less like your sliding off of the boat) and a boat that's sailed flat is a boat that's sailed fast.
6. Curvature of the foredeck. The more curve over the crown of the foredeck (both fore/aft and left/right) the stiffer it will be once glued down. Don't get carried away - this is 'tortured' plywood, and will be difficult to glue if too tortured.
7. Height of the foredeck. A high foredeck will give more bouyancy to the front tank (important to keep from submarining with the spinnaker up in big waves) and will also result in having slightly less water coming into the cockpit in choppy conditions.
8. Mast forward, Centreboard aft. To achieve the best balance between the sails and the centreboard (for a neutral helm) the mast should be maximum forwards and the centreboard should be maximum aft. This applies in particular to wide-bow boats - 'skinny' boats may not have enough bouyancy to feel good with the mast maximum forward.
9. Mast spur height. The mast spur should be as high as permissible - this gets the sail that little bit higher in the air for a little extra power.
10. Minimum weight. It goes without saying that you should try to achieve a minimum weight hull (175 pounds with all fittings attached but no string and no foils). But DO NOT sacrifice stiffness for light weight. A flexible hull is a slow hull. Fireballs do not have a minimum all-up weight, so get the ready-to-sail weight as low as possible. Here are some ideas: minimum weight centreboard; minimum weight rudder; minimalistic rigging; lightweight modern lines, blocks, and cleats; synthetic (vectrus or technora) trapeze lines; synthetic (kevlar or spectra) main halyard; lightweight modern mast, boom, and spinnaker pole. Even if you have to add weight to the masthead to meet the measurement for minimum tip weight, it is worth keeping the overall weight of the rig to a minimum.
11. Details details details - ensure that all lines run fair with as little friction as possible, ensure that the foils are wet sanded to perfection, ensure that the bottom finish of the hull is perfect, ensure that the slot gaskets are in good shape, ensure that the joint of the transom with bottom and bilge panels is sharp and square, ensure that the boat is as symetrical port/starboard as possible...