David drew this doodle in less than 15 minutes during a meeting. Practice wherever you can.

Here are some hints and suggestions which I have picked up over the last 30 years or so and I hope that you will try some, if not all of them.
Remember, there are no right or wrong ways in art – if something works for you – do it. There is only one rule – there are no rules!
If you want to use black – use it – Turner did!  If you want to use photographs – use them. (Most painters use them but pretend they don’t!)

There are only two things which come close to be rules:

1. Drawing - This is the most important thing that any painter can do. It teaches you to SEE instead of just looking and then teaches the hand to put on paper what the eye sees.
Draw every day.

2. Practice - Don’t expect to get it right first time. When someone learns to play the piano they don’t start with Mozart’s 21st Concerto - they start with scales and practice them. Painters must do the same – Practice, Practice, Practice. — David McEwen