So I think I'm getting to a point now where I need to learn about colouring because I get to a point in my lineart where even though the lineart is mostly correct I end up making my artwork look really cheap or unprofessional.

I'd really like it if you guys tell me how you do your shading/colouring or even better could point me to some tutorials that give some detailed info on some colouring and shading techniques that will help me get that finish that other pieces of artwork have?

slap some colour onto the page and then slap some other colour onto the page. that's usually how I work.

sometimes I start out with base colours and then work in my shadows and highlights. really though I take a different approach with most of my images depending on what I really want the image to feel like.

Make colors your friends. I picked up a tip from Linda Bergqvist (you can read about it in her very long meet the artists thread on CG talk) basically try to describe everything with color, even how you are feeling today. I think this is a great start for building a relationship with color. A practical tip which to me made all the difference is to start by defining your palette. Just slap around color on a separate layer and try to visualize what's in your head using color. Also make sure you have good understanding of value, these to can't be without one another. :)

Onatopp:

Make colors your friends... this is a great start for building a relationship with color.

But don't get too close. I made that mistake. Yellow kept running away from my advances, which made green jealous and it started to see red. I ended up black and blue.

Keep it platonic.

pixmaker:

so everyone does the same method.  the willy nilly color method and adjust as you go. 

Not really, I have a rough idea in my head of what colours I will use before I start... then I ignore that and just splodge colours all over the place (I learned that from fabledgoat).

I like to start black and white, or at least grayscale. However, I suggest studying color theory. It's a good skill to make your colors like each other to your eye. There's complementary colors, triadic, monochromatic, or neighbors. You've also got the intensity and brightness going on. There's lime green and sage green, both kinda light, but one is muted, right? You can make colors duller, or less intense, by adding a bit of their complement. If you do this, I suggest using that complement elsewhere in the painting (it will make the picture look more unified).

Also, learn how reds, yellows, and blues can all have cool tones and warm tones. Don't make artwork with a cool red, cool yellow and warm blue unless you have a reason for it! 

It sounds counterproductive, but try using as few colors as you can.

Good Luck. 

I work out my basic colourscheme before I do anthing... I research schemes & lighting that might match the atmosphere I want, decide if I want to do monochromatic, complementary, triadic etc etc, choose hues, then check they work tonally & set them down as a flat palette.  Then I pick from that palette as I do a basic coloursketch, making sure I get the right amount of each colour in the right places, followed by a final painting based on the sketch. 

Having written that all down, it's a very long-winded method isn't it? :\