>>5071631What part of it are you having difficulty with? Is it the layering, the colours, the forms of the shadow, etc?
Depending on what part you're having issues with, that'll effect what you need to focus on exactly. If your colours look like shit, start out by colour picking from images you like until you get a solid understanding of what looks good. Study colour theory and relations by taking a bunch of images you like, putting them in your program of choice, and colour pick from different sections, comparing how the colours interact with each other, is a good way to start breaking through with muddy or shitty looking colours.
If it's the actual "layering" technique to the colour, set your brush to a lower opacity and build up areas of colour. You can get the same feel with either a completely hard brush, or a brush with only a little bit of blur/blend to it, but at first you'll want to avoid blending anything.
There is no easy mode, and no tutorial which can teach you how to do this. It's 100% practise, trial and error. The more you do it, the more your brain figures out how to make it look correct. Starting out is the hardest part, but just stick with it. Best thing to do is study illustrations you already like, but it's important not to do this when you're already frustrated with yourself.
Don't go straight from drawing something else and feeling like shit, to trying to do a study, you won't end up focusing as much, and in turn won't learn as much.