We have a large quarter-circle tank, about 300L in size I think. The radius is about 90cm-1m and it's about 1m in height as well.

Plumbed in so the water changes are all run through the filters first and done automatically so the floor doesn't get wet. Large strip light at the top and a large heater.
We have some rocks, old ceramic pipe things and pottery, petrified wood and about 10 plants.

Fish: 2 cooli loaches, 3 clown loaches, 10 neon tetras, a plecko, a dwarf gourami and 3 hatchet fish. We had some "golden wonders" but turns out they are predatory (the fish shop did NOT tell us that and knew which other fish we had) so we did have more fish but they were attacked. DH got rid of the nasty fish and we'll put some more in in about 6 months' time.

The fish know when it is time for food (6pm) and if they are forgotten (DH usually feeds them, but sometimes he's busy) and I sit down after we've eaten they will come and shoal near me. The second you lift the lid of the tank they're all up near the hole in the condensation catching bit of plastic ready for food, it's quite cute. They learnt a trick!

Tips for new starters: Plan your tank. Pick your favourite fish then ensure you only stock your tank with fish they will get on with: predatory fish can cause distress, especially to young children who don't want to see Nemo being eaten when they wake up (didn't happen to us thankfully!). Also try to get a mix of top, middle and bottom dwellers in a large tank otherwise there will be large areas with no fish in. If you need to treat the water, don't stock immediately, let the tank mature first.