How do i make my garden look good and not depressing / boring please? I am clueless!

Drip system probably best for pots. Although a specialist nursery near here refers to it as the "irritation system" because the drippers get blocked. I notice at most nurseries that have them on, e.g. potted trees, that they have at least two drippers per plant, to cover for "one got blocked".

I use a ring (or a double-ring in bigger pots that need more water) of leaky hose around the inside of the pot, connected to a TEE onto semi-rigid pipe. No blockage problem, but you can't just "stuff it in a different pot" like you can with drippers on fine "capillary tubes"

 

It's a bit personal preference, but I would go even darker - I prefer all out dark greys/blacks to the "fake wood" appearence of brown, which never seems to age as well (though I am sure others would feel differently!) This sort of thing:

or

For the shed and bench, I would say completely personal preference - I would probably go lighter blues or greens, maybe a couple of different shades for the main body and the trimmings, but I've seen people be more adventurous with brighter colours and oranges/reds/purples etc that also look very good.

I'm a big fushsia fan, though one thing to bear in mind is lots of varieties aren't hardy and so you can risk loosing them over winter. It depends a little on where in the country you are; so far I've not had any problems in my sheltered south west city garden, but if you're further north/more exposed then that could be a bigger concern.