Hi Sean_Buckley
The important thing is moving the beneficial bacteria. This is clinging to all the surfaces such as the filter and the media inside it, the gravel, the plants and decorations. There is very little beneficial bacteria floating in the water.
When you are ready to make the switch, give your gravel a good vacuuming so you are transferring as little dirt as possible. Remember, the bacteria are ON the gravel, not in the dirt. Any soil you cannot get out might cloud the water in the new tank, but the filter will eventually remove it.
Bacteria dies when it dries so keep it wet at all times. Just unplug your filter and move it from one tank to the other without cleaning. There is time enough for that later. Lift the plants and decorations and move them quickly to the new tank and get them right underwater.
If you transfer half of the old water to the new tank it will be plenty. This will help keep the tiny bubbles from forming on the glass when you use all new water and will reduce the amount of sediment that is transfered. Fill with new dechlorinated water. Adjust the temperature and you will be ready for the fish.
You might lose some of the beneficial bacteria in the process, but they will soon be reestablished in the new tank. It might be a good idea to test your water until you are sure it's OK, but the fact that you are moving your fish to a bigger tank is in their favor since this tank will be less heavily stocked than the old one.
Good luck and please let us know how things work out for you.
