Main Sail Shape
To some extent it depends on the boat and the conditions of your sails but the most effective way to blade out (flatten) the mainsail you would tighten the main halyard, outhaul, and mainsheet and lower the traveller to leeward. Flattening the sail greatly extends the range of the sail before you need to reef. There are of course limits as to how much you can extend the range before reefing is necessary or simply more comfortable.
How effective flattening the sail turns out to be depends also how easy to use and conveniently located your hardware is, and the conditions of the sail. I don''t know if you are still sailing with the original sail that came with the boat but I would guess that you probably are. Over time sails stretch and sails get more stretchy. In a gust and older sail will increase in depth and automatically power up just when you would like them to flatten.
Easing the sheet can help keep a boat on its feet but initially easing the sheet powers up the sail and so increases heeling and weather helm. Easing the helm eventually does reduce weather helm but at the price of pointing ability and speed.
Also you really don''t have the some of the newer or higher performance options such as controling mast bend, which is probably the most effective way to quickly blade out a sail in a gust.