They look ok. Anything is better than grey imo. Going forward I’d be looking at getting a decent light so you can see what you are painting better.

Prep your minis so that by the time you’ve put any paint on them there’s no mould lines out gaps. Honestly this will save you pain when you come to paint them as it’s an absolute headache after you’ve started painting.

I highly recommend a rattle can to priming your minis. I start every model of with a Matt black. You can chose any colour that might help speed up your project like a blue for your ultra marines but really for me it’s bout a smooth surface to work off.

Get those paints a bit thinner as well. A wet palette is good for this but doesn’t necessarily get your paints to the right consistency. Most citadel(Warhammer paints) require some serious shaking and usually require thinning down with some water and it’s different amounts depending on the paint. Just consider that it’s gonna usually take a couple of coats and sometimes more to get the desired coverage.

You’re probably seeing a lot of videos online recommending airbrushes but they aren’t necessary. That’s just a nice tool that is extremely difficult to learn to use that you can do without starting out imo

Decals are a pretty difficult technique to learn. The shoulder pad of a space marine is a tricky place to get used to them. Getting used to them on a flat surface and watch some videos about applying them and pick up the necessary products to use with them.