Dont try Marine first
Its SERIOUSLY difficult
Get the biggest tank you can, bigger is easier.
Same with chickens really.....
If you do get a big tank, get a big external filter.
I have a 300 litre tank and a canister filter rated for 400 litres.
I wouldnt say proximity to water matters, mine isnt, just buy a bucket
Cycling can be a bit of a religion to some people but here goes.
Fish eat fish food.
Fish Turn fish food in ammonia.
Amonia is poisionous to fish and will kill them in even small amounts.
Different Bacteria turn ammonia into Nitrite
Nitrite is even more poisionous to fish and will kill them in small amounts
Different bacteria turn Nitrite into Nitrate.
Nitrate is poisionous to fish in large doses.
The only way to remove Nitrate is to remove water from the tank and replace it.
(well, there are ways, but not for the first timer)
If you buy a 100L tank, and fill it with 100L of fish, the ammonia level will increase faster than the ammonia eating bacteria and your fish will die.
If any of them somehow survive, long enough for the ammonia producing bacteria to grow, well, the ammonia producing bacteria start churning out even more toxic stuff, and they all die of nitrite poisioning.
That said, I cycled my 300L tank with 5 Neon Tetras, and tested the ammonia daily, never moved. I then added fish in small numbers until I was fully stocked.
Its concentrations of ammonia that matter and my 5 tetras were never to make enough fast enough to be a danger to themselves in that size tank.
I change 10% of the water each week with a gravel vac.
Borrowing a friends filter is a quick way of speeding the process up.
If you google 'fishless cycle', you should get a good guide.
Really, you need a liquid test kit too.