Yeees. That’s why I suggested something simple in 3/4 view. By simple I meant something along the lines of a wooden toy locomotive, or a smart phone, from a reference photo. Not your own design.
The first one is in 3/4 view. The others are not, and with those you’re going back to your comfort zone. The first one is a solid try though, so maybe more of that, but just with things you already have a reference photo of. The reference doesn’t have to be in 3/4 view, as long as you have enough images or information to understand what the thing you’re drawing/painting consist of.
Would also suggest to forget the word “concept” for now. To be brutally honest, it sounds like an excuse of doing or not doing something. The reason for being so negative about it is because it’s not helping and I suspect you’re missing many important points because of that. Main one being the difference between drawing and design, and practicing those separately.
A concept communicates ideas to solve a specific problem for a specific purpose. If you can’t list the project, purpose of the concept in that project, the requirements for the concept, the backstory you had or developed and the references you used to pull the ideas from, it’s not a concept.
Design/concept work is very different from practicing drawing and painting. When you practice drawing, you’re focusing on improving your ability to visualize anything. Drawing and painting already has so many things going on that you need to implement or develop a process that takes you through all the important parts of it. Adding design to all of that is like trying to get in a better shape by lifting excavators.
It’s the same as trying to get into 3D with Blender, being new to both of them, and starting all of that by modeling a human head or a car of your own design. Starting modeling with a car or human head is a big rookie mistake. Starting modeling before the design is done, even bigger rookie mistake.
Theoretically you could do it if you knew to gather the list of information you have to learn and practice, preferably in a hierarchy to get the order of things right, and have the patience to fail again and again knowing it’s the rocky path you’ve chosen for learning. Haven’t found a single learning resource that would teach all of that from the beginning to the end, probably because it would contain material to go through for a few years.
The reason I linked to the example I posted in another thread, http://pasteall.org/pic/show.php?id=120277 is because it shows a simple example of a drawing process. The subject matter is simple, just a twig, because it’s not important. The process itself is the important part, where each step is there to solve a set of problems before going to the next one, improving the result in stages and saving time by fixing mistakes early. It doesn’t go into rendering a fully textured and detailed image, and is not the prime example of a one size fits all process for everything because there isn’t one.