Fair point. A few good ones have been listed already, but to get us back on track, a few things that come to mind:
1 - as mentioned flipping the paper. I’ve been taking this another step by scanning my underlay, flipping it in photoshop, warping/liquifying as needed, printing back out and overlaying it
2 - reference. Surround yourself with lots of reference. I use pinterest a lot for this. Not so much sketching reference but lots of benchmarking contemporary details, executions, and CMF palettes.
3 - studying how other people do it. There are so many great youtube videos out there. I try to watch a few a week and try out what people are doing.
4 - changing mediums. The human brain is programmed for pattern seeking. This is really positive when driving to work (ever have that moment when you get to work and realize you don’t remember the drive at all? That is your brain finding patterns and going on autopilot). Your brain being in a pattern is not good when ideating. I find if I always use the same medium I can get stuck. Sometime switching pen types, or to pencil, or paper size, or analog to digital just helps shake things up… likewise changing musical genres while sketching can help.
5 - pin up your work. It seems silly, but for some reason if you pin up your work and step back it just helps. When working on a project I pin everything up as I go. It helps me see what is warn and also helps me to see grouping and themes in ideas and shift the bulk of the work one way or another. I can more easily see if the bulk of the exploration is focusing too much in one area, or if the majority feel to conservative, or too far out there. At an early stage i’m trying to show a broad variety of ideas that are still mostly within the scope of the project (a few outside to keep people on their toes). Pinning up helps me to do that.
6 - goes without saying but underlays underlays underlays. I rarely show a sketch that hasn’t been overplayed 3-4 times or more. The first underlay is usually just a perspective page layout. I might use that underlay across 10 concepts. The second and third underlay I’m exploring the idea, usually just functionally blocking things in and drawing through it, maybe roughing in some components. The last overlay I’m getting it all to work visually and making sure it reads easily without needing to say much. Sometimes those early underlays can be CAD based mechanicals, a photo, and old sketch, or a rough new sketch, whatever it takes.
7 -up front strategy work. This isn’t so much about sketching as it is helping clients (or peers or higher ups) understand and agree to a set language and align on parameters. Before I sketch I’ll often rough in a series of solution spaces both functionally and visually for the concepts to reside in and a few frameworks that will help rank and judge solutions. This also makes my sketching a lot more efficient. usually a few good ideas will fall outside those strategic areas and i’ll have to go back and touch up the frameworks, but it helps me be more focused. And if several designers are sketching the project it helps divvy up the work by solution area.
8 - textures. A more minor one, but having a stock set of textures you know how to apply (leather, textile, perforations, glossy, woodgrain, brushed metal) helps you be that more efficient. You don’t need to worry about it in the moment.
9 - humans. On the same note as textures, having some stock ways you typically show human interaction (hands, feet, figures sitting/standing and the like) really helps you not work about it in the moment.
10 - of course the way to work on all of these techniques is practice. I know a designer who does a 30 minute practice sketch everyday when he wakes up. I try to squeeze one in here and there. Sometimes just a doodle in my notebook. This year I’ve been diligent about doing one a day everyday. Honestly I didn’t think I’d see that much of an improvement (a stupid and cocky POV). I feel like I have improved a lot, not only in my sketching but in my clarity of thought on the page. As my boss at frog used to say “You do your best thinking with your hands” something about working through an idea, whether that is on the page or in the metal shop, that advances it.
11 - sketch with others. Sketching with others can really help. There is an exponential momentum to 3 or 4 people sketching together, doing overlays for each other, adding to each others ideas. It can be really powerful and fun.
12 - go back and forth. Sketching isn’t a phase, it is a way of thinking and communicating. Research a little, sketch a little,e build a little CAD, sketch a little more, make a physical mockup, sketch a bit. Every point in the process is an opportunity to improve the design, and you might do that with a little sketching.