MSPaint is not very good, especially if you are gonna try to do anything bigger and need proper palette management.
There are free options which are TONS better such as Grafx2 or Graphics Gale.
Seriously, do yourself a favour and stop using MSPaint, it is a sore excuse of a program. Learning a program that is geared towards pixelart, such as those I mentioned, or commercial stuff like Promotion, will help your workflow in the long run and you will be able to do better looking stuff in the same or less time than working in MSPaint.