Always use oil paints which is called wet on wet painting. This way you can wait a couple days before you go back to it and it won't dry out. It gives you the ability to change colours or shapes in the oil painting as you go along.
There is no need for stress when you're oil painting. Like my artist friend told me from New York there is no such thing as a mistake there is just something you can change from day today until it suits you. A little quiet music while you're painting for an hour or so at any given time is better than taking yoga and I know because I took years of yoga in my 20s.
Also...art is in the eye of the beholder...so really anything goes as long as you're happy with it!..that's the key. I'm not doing it to relax...I'm relaxed enough...just something I've always thought about it and have enjoyed drawing for the grandsons...that's usually the first request from the little ones in Illinois....the middle child always requests Noah's Ark with ALL the animals, lol. My son's boys are pretty talented artists too, got it from their dad. My daughter and her boys can't even draw a stick figure.