Very nice! Your character has such pretty colours and a cute symbol.
I am not familiar with Corel myself so I'm not sure how it works, but usually the easiest way to go about colouring digitally is to create a separate layer for the colours. You can do it by duplicating the lineart layer, that way you can use the lasso or some other helpful tool, then fill in the rest by hand around the linework. It doesn't matter if you go over the lines as you'll still have the original lineart layer on top that will cover the messy bits. At least this is how I do it, though usually I start with a blank layer and colour everything by hand...