Mister Coaster,
Where to start. Tanks. When I started in this hobby, tanks only came as rectangular boxes. A lot of that had to do with the materials being used in the construction. Now, walk into any store that specializes in aquariums and you will see aquariums in a variety of shapes and sizes. What's right for you?
You need a tank that will fit into a corner and you want to dabble with the natural plants. The three most important elements for plant growth are water, light and nutrients. All of these are growth limiting factors. Water - I think we have that covered. That leaves light and nutrients. In general, you want to have a minimum of 2 watts of fluorescent light per gallon of water. This is assuming that you don't select a tank that is taller than it is wide. Just like with terrestrial gardens, not all plants have the same needs. Think about your lawn. You can get grass for the shade, grass for high light areas, grass that needs very little maintenance etc. Same goes for the aquatic plants. Plan ahead, look at the requirements needed for the species that you select and get the appropriate lighting. Personally, I would shoot for 3-4 watts per gallon.
Next is the light fixture. Standard fluorescent bulbs come in 2, 3, and 4 ft lengths. All other lengths are a combination of these bulbs. The fixtures themselves tend to have reflectors that work best over rectangular shapes. Round bulbs have reflectors that throw light in a circular pattern, long bulbs in a rectangular pattern. Corner tanks present a challenge to lighting because you want to maximize coverage in a tank that is not a rectangle but economy would dictate fluorescent lighting (because money talks!) And design esthetics also counts. You want a tank that is sharp looking, not something that has been cobbled together! There are a ton of lighting options and I'm sure that actnic will have his preference - I know him too well not to thrown in on this
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Tank shape and design. Don't get a hex tank. They are too tall and ugly. You see silicone joints every 8-10 inches of viewing space. My preference is the Corner bow tank. It is a wedge-shaped tank with a curved front (think pie shape wedge). It has enough space on top for a variety of lighting options and most manufactures have finished cabinetry for these tank by virtue of their shape.
And don't forget filtration. I would go for a canister filter that sits below your tank. I prefer Ehiem filters. A hang on will take up space behind your tank and the tank will not fit in the corner very well.
Nutients I will leave for actinic.
There is a ton more, but this should get you going.