Drawing from "direct observation" is the most challenging and rewarding way to draw.  Going out into the world, and making a sketch from just looking at an object, like a car, is a great way for an artist to develop skill. 

People stop to say hi and watch the drawing progress. I find it a delightful experience to work in public places and interact with people.
A little over a year ago, dissatisfied with my growth as an artist, I resolved to better my skills and produce more drawings and paintings, as well as overcome "artists block". 

I began by setting a goal of drawing for 15 to 20 minutes each day and  start a new habit by working at the same time and in the same place.
I worked on "Practice" drawings, exercises from a beginning drawing book to reinforce my fundamentals,  and relieve the pressure of "What" to draw.  My sketch pad, a couple pencils and eraser was kept handy, and in plain view.

Halfway through the third week, the daily routine became automatic, I had formed a habit.  My mind was vibrant with new and revised ideas about what to draw and paint.  With my drawing skills gaining confidence, I began looking free up more time for drawing, and start painting regularly.

I learned a valuable lesson about spending a small amount of time on a daily basis to build habits and attain goals.