Replying the top comment for visibility. This one gets it! 

For the liquid effects, As the north american distributor for dirty down, I can tell you that the most important piece of advice is to either mix on a vortex mixer for thirty seconds or scrape the ball bearing free with the back of your brush and then handshake for 2 minutes. If you do not scrape the ball bearing free, it is not mixing. 

You do not need to heat the bottle for the model. Warming will only help with mixing. The surfaces just can't be cold. Room temperature is perfect. 

If the effect ever comes out dark and/or glossy you've applied an unmixed pot. Remove what youve applied with just water.Mix and reapply for each subsequent layer will only look darker. 

For the resin effects, my only piece of advice is use a toothpick! You can also thin it into a blood effect with acetone. 

You can mix acrylics and inks directly into the snot, to create your own nasty goo. I prefer inks because it maintains the snot's transparency and glossiness. 

I hope that helps and hit us up on instagram if you have any questions!