Get as many containers as you can!
Switch off all your electrics!
Empty out about half the tank, putting as much water as you can in your containers. You don't
need to keep much water, but it does help prevent any issues with pH or hardness shock.
Carefully pull up your plants and put them in one. Take out all your decor and put in another. Now catch the fish and put them in one of the containers as well. If you have a lot of fish, you might want to put them in two or three. Cover the fishy containers with towels or blankets to keep the heat in and the fish calm.
Remove heater/filters and put in one of your containers to keep the filter media wet.
Now you strip down the old tank and put the new one in it's place. Add substrate to the new tank, the water from your 'spare' containers (ie, the ones with no fish in). Replace your plants and decor, heater and filter. Add the water and fish and then top up until the tank is full.
Switch all the electrics back on.
Have a nice cup of tea (or a beer, or two, or three) and spend the rest of the day fiddling with the plants and decor 'cos you don't like where you put them