I am new to the digital medium and work professionally as a tattoo artist and looking to save valuable time through the digital medium to design my custom work.... and i am working with a limited income, therefore, would like to make use of my mouse as opposed to a pentab....

i want to be able to simply scan in a rough sketch, be able to ( as precise as possible ) select just individual areas of the drawing to add color and depth... much the same way you would airbrush... i need freedom to go outside the lines of my selection....almost as is if its just "cut out"....lets say for ex., just the pupil of an eye .... i would just want to select the small circle....quickly fill it black.... "deselect it".... select the color part of the eye....fill it blue then "deselect it" and have a crisp edge between the black and the blue without having to spend the time it would take to do it precisely like you would with good ole pencil and paper....

is that possible in this program and any advice would be greatly appreciated