I just recently started trying my hand at modeling fondant. At first I was just using homemade MMF then I tried some of the wilton store bought kind. With both I've had trouble with preserving the texture/stiffness after coloring them. I've used gel and liquid colors and after I color them they seem to lose their stiffness. Should I be adding more powdered sugar to it? Or should I be using powdered colors? Also I was wondering if just creating the figures and then painting them the color I want would be a better course of action. If I did paint them would the paint then bleed into each other when I try to add details?

If you add a lot of color, the gel can change the texture of the fondant, you should add some conf. sugar. If they are just soft, that is probably from the heat of your hands, you can wrap it in plastic wrap and let it rest for at least a few hours.

Wilton fondant holds up pretty well for figure modeling, but you could add 25%-50% gum paste to it or a bit of tylose to stiffen it up if necessary.

I don't have much experience with MMF (its been a few years since I made it, but didn't love it), but I do remember that MMF is much softer, you should add some gum paste or tylose powder to it so it is more workable for figures.

Thanks a bunch! For adding the gumpaste do I add that as a powder or just knead gumpaste and fondant together? Your comment helped me a ton, thank you!

Your very welcome, happy I can help. You can just knead the fondant and gum paste together OR add tylose powder.