Hi there! I feel like I have so many questions. When I painted last time, I got the paint too thick. How much water do I need to add to my paints? and how much of the medium do I need to put in them to keep them from losing their pigment? I use Golden fluid acrylics.
Thanks,
Julie
https://discourse.bountifulbaby.com/t/golden-fluid-acylics/82843/3
This may help you. If not you can use the magnifying glass to search and find lots and lots of info on your paints and tips and tricks on using and mixing etc 
Have fun
I use liquitex. I do not use any kind of retarder. I do not prep my kits. Most of the Artist on here use a retarder and prep their kits. I add a pea size of Liquitex Matte Gel to my paint, which is a glob of paint. Then I add enough Distilled water till it is milky/creamy thin. It depends on what you think is best. Since I am in a Dry climate I can make it a little more creamy than milky.
Practice on a limb and let it dry for about 20 minutes to see if you like it. Then adjust accordingly. I make enough to paint a couple of dolls just to paint one but I throw whatever I don’t use out after I am done. I’d rather have too much than too little. Good Luck finding your formula!
I also use the primary method.
I add about 2x medium than paint, plus water until I get the transparency I want. I test it on a paper towel.
I prefer to add more medium than water to get it right if too dark.
After 3 paint layers I add a layer of UMG, by itself, watered down just enough to spread nicely, lol.
What’s that? Umg
Ultra Matte Gel, I was being lazy 
lol It’s okay. I don’t do well with abbreviating lol 
How transparent do I need to get the paint to be? When I watch videos of some painting in washes, It looks like you can barely see the paint color and it almost looks like water. Lately, I’ve just been doing the paint, medium and water without retarder.
I make mine milky looking not creamy. Though I do creamy on my Alternatives.