I made a fist of that

When I was young I thought that you had screwed up if you made a fist of something.

In fact it means the opposite*

* After further research I find that it is complicated!

In the USA "To make a fist of it " is to do a good job..

For clarity you may say "To make a good fist of it"

For the opposite you can say "To make 
a bad fist of it.

Or if you come from Yorkshire "To make a right fist of it"