I think you have some good skill already! Just keep sketching. A sketch a day keeps the doctor away.
Try to exercise lots of product/stylings. Organic, simple basic, faceted, sci-fi whatever. Also products have insides to. I’m relearning this the hard way right now Try to think about the mechanics how it will work and try to sketch that to. As for sketching-inspiration I suggest you search for problems with current products/situations in your everyday life. Got frustrated with your camera, GPS, door, car, kitchen tools,…? Redesign them while sketching. This way you’ll catch 2 birds with one stone.
It is important to sharpen those sketching skills, but doodles are different. Try to do some serious pages, where it shows that you thought about layout, page balance, callouts, and most importantly, your design.
Top priority is projects, you need at least 3 projects, load your portfolio up with projects.
As mentioned, good start already. Afew suggestions:
scan your sketches, or at least photoshop the levels to a white background. I had a professor that would mark any project an F that didn’t have all aluminum tacks, as he would say “if you can’t care enough to put your work up with 4 nice tacks, I can’t care enough to give you a grade higher than an F”… harsh, but he has a point. If you want serious feedback, be serious about presenting the work nicely. It sets the tone.
try sketching around an idea. Instead of having several random sketches, try thinking of a singular idea and then exploring multiple variations of that idea on the page. The page itself should read as a whole.
as stated try some different levels, looser, tighter…