Here are a few things that I've found
particularly useful in an urban enviornment.
1. ideally plan where you're going to paint beforehand.
Rubbernecking while you drive around looking for something is not good and wastes time. Find a spot the day(s) before. And when you find a place, also figure out where you're going to set up - parked cars, telephone poles, driveway, entrances, bus stops, and the list goes on of things that could prevent you from setting up where you'd prefer. Often you'll find just one 3-foot square spot that works. And plan where you can park for the day/time you plan to paint.
Pack as much of your gear as you can the day before and
use a checklist. I have a bag that can stay open, so I can easily see and get stuff - and I always pack it the same way so I know right where everything is. I'm not all that
self-conscious when I'm out, but I don't want to make a
spectacle of myself either.
2. Keep your painting footprint as
small and contained as possible - I try to set up against a building, or pole, or curb, etc,. so there is a clear path for people around me.
3 THere are different philosophies on palettes, some say just take three primaries and white - "you can mix any color with those" -- maybe - but do you want to spend
limited palette space and time mixing -- or painting? And if you use some type of paint container, like a "palette garage" - you can have a dozen colors at your disposal without bringing a single tube of paint -- except white
always bring a tube of white.
4 I found that in the city where there are so many things and activities, etc., your
brain/vision edits and invents a lot of stuff. So you may think you've purveyed the scene well, but once you start painting you discover things aren't arranged or appear as you thought. Again
advanced scouting and thinking when possible is always a good idea.
One thing I found weird. When you work with 2D pictures and dark tone is limited. Outside you see everything in 3D. Depth has a whole new meaning, and so do darks and shadows.
I would have to close ( or cover ) one eye a lot to avoid getting overwhelmed.