First off- when your trailer is level stick on set of permanent levels to the front and side of your trailer. You won;t have to guess if your trailer is level. Levelling front to back is fairly easy using tongue jack – however levelling from side to side is different story. Do NOT use your stabilizing jack to level your trailer. They are not built to carry that much weight. You can crack you floor or damage your frame trying to use those jack to level your trailer .You have to have something under one of the wheels. Many people use a levelling system ( popular ones are BAL leveler and Lynx leveling) other are happy with pieces of 1″x8″ pieces of wood under the tire.
Park trailer on your site- roughly placed where you want it to go. Then put your levelling block or wood either just behind the wheel or just in front and drive you towing vehicle a bit forward or behind- depending where you have placed the leveling block. Recheck with your levelling tool. When level, chock the wheels, unhook, and pull ahead.
I can tell you with the BAL Leveller its is a breeze. You just place iunder the wheel and crank. Works like a dream. This is easiest. You only need one and cost is about 65.00 USD.