Really counts on your subject matter. If your doing figures, some 2’s, 3’s, and 5’s, quicksketches are good to warm up with. If doing environment some value thumbs are a good warm up.
For Environment thumbnailing
James Paick is always good. I’ve taken his environment class on CGMA and it helped a ton.
Intro to Compositions are interesting. I enjoyed his line theory. If you scroll down he has a FREE video to watch.
Also has a FREE Environment video to watch.
I enjoyed both these Etyan Zana videos. Also Etyan is incredibly adorable I found myself smiling many times through his videos.
Count really what your focusing on, if your focusing on getting values in, anatomy, or gesture. Watts tries combining all three. But sometimes does focus on one thing, really counts on what they are demoing on. Usually though it’s gesture, scaffolding/anatomy, lay-in/shadowmapping, then filling in tone. You can choose to focus on portraiture or full figure. Here’s some examples of quick sketches by the teachers.
vvv Essentially this but trying to consolidate the process in under 2-5 minutes.vvv
John Park has a lot of great and quick processes for thumb nailing mechs and getting you to think outside the box some.
Usually speedpaints help in this area. Sijun used to be a big place for them, CFSL ( french) has a forum that’s pretty alive. There’s 2 speepainting facebook groups, Spitpaint which is 30 minutes and Super Speedpainting Funtimes which is 60 minutes. Many times people will post up their processes or brushes so keep an eye out.There are a couple groups that host them. I’m fond of Sparths speedpaints.
I’m not sure how long Robh Ruppel spends on his paintings but I really like the look of them.
Keep in mind what warm ups are. They are to reacquaint you with your process and get your legs moving again. It’s to help get all the rust out of your system. So try and keep things short.