Surely there must be tanks that you have seen, even the really proffesional ones online and thought OOOh i like that etc.
Give yourself a start point, that piece of wood will look like an afterthought unless it goes with its surroundings and has some context. You should see what the fish prefer too, the sand is great for the cories but they also like somewhere to hide. Some of the gouramis do too.
Others like silver dollars will eat plants, other fish prefer rockyer layouts. Try to imagine a big picture.
Personally i'd be down to the diy shop for some hardboard, black velcro and a tin of black paint. Or black and some green go nuts.Paint the backdrop and stick it on.
Then i'd bin that hideous stick on thermometer on the right and find some black suckers for the air line at the back.(do you really need it). Finally i'd site the heater as close to the filter as possible so the filter will help spread the heat around the tank and it keeps all the uglies in one place (look at my sig, there are 2 heaters and the filter inlet and outlet in there) so they can be hidden with something like pennywort.
THEN i'd worry about the wood.
I almost sound like i've learned something on here
