Here is a start with lots of mineral spirits in the grey paint. Now, if you can just continue with ever more paint in a slow progression.....
- Put out more than enough paint. Use it to get the required viscosity.
- Practice taking appropriate amounts of paint to get colour and maintain desired viscosity.
- Hold the brush properly to let the paint come off.
- Listen and feel the paint coming off the brush.
- Practice increasing the viscosity in small amounts for each layer - ie stop using mineral spirits - fat over lean
- Experiment with mediums, raw paint, mineral spirits, or combinations.
- Scrape off excess with a palette knife.
- Remove excess with a rag, paper towel, or finger.
- Take a break to let the paint set up.