Anyways, ty brah 🥹

As far as actually colouring itself, all I really have to say is block out certain shapes and shadows using lighter colours first, then darken them as you continue. Layering is key as well as knowing the basic colour theory fundamentals. For the blue, i used a lot of similar tones to build up contrast (although, the yellow helps). Midtones such as green could be used and combining yellow and the blue made green already(obviously), so eh. I honestly used a lot of the primary colours, since it fits in with the somewhat vibrant colour scheme.

I've been drawing my entire life and have only recently started using colours in my work 😭 I think I've been drawing for about the same time as you, if not a bit longer. I'm much better at sketching and I'm kinda butt as colouring, so I do hope I helped at least a teeny bit.

Remember, it's not the supplies itself, but your own creativity and skill set that will make a piece look amazing ;P