This is just a fast guide to rendering with MS paint
today we will be rendering this image of Simba:

When pasting your image make sure you have a colored background frist and trasprent (you can find this on the select menu) pasting on as this will remove any pure-white color wich will effect the render later on

After cropping your image to what you need you can start your render, when rendering this tool

Will be your main tool used, it frist comes out as a stright line but after placed you can move it twice to curve it, this may take a few trys to work out.
Your next step is to just render what you want to use, you don't have to use black any color will do, eg if rendering scar use a light color , i tend to use red but for this guide iv used black, for your frist  few renders i would recomend not using the 1 pixel size when rendering

The next step is to make the lines white, if you have used white then you can ignore this step, so long as you have no used the 1 pixel lines you should be able  to color any touching lines white using the bucket tool

The next step is the most important part, please note : this step will not work if you have not used white lines, you will need to push CTRL + E wich will give you the following box, 

All you need to do here is as the image shows set it to black and white, this will give you an image somthing like this: 

(Please note ; This image was taken after i saw some mistakes with the frist render, so things like eyes and teeth won't apper in the next sample)
the next step is the same just changing it to color again so CRTL + E then color, this will fix up a few small flecks and look how your lines will be only the wrong color

Now this part is weird, you can just invert the colors and continue but iv had problems with this so i allways open another paint file and copy and paste it there as this fixes the problem, next you want to right click the image (make sure you have select ... selected, as seen above) and invert the color, this will make your lines the right color

then you just color as you like, my advice would be copy the lines and have them somewhere so after you color you can paste them over incase the coloring runs over the lines 

do remember to fill in any small spots left over , this isnt important but it will look better with out them.
enjoy your rendering!!

please let me know what you think, if there is interest i can make a few more (fourm) guides on using MS paints and tricks iv learnt over the years.