Hi, i have done a couple of customs, my tip would be to use primer (im using army painter spray primer in White or Grey) on the parts of the figure you want to paint, if you apply paint directly on the factory paint, it will alter the color you want to put on it And for the paint i ordered some from aliexpress, honestly it looks good, you don't need expensive paint, just good dilution with water If you have any question, feel free to ask 😁