Welcome friend! I recently committed to improving my art as well and I think you're on a great path! Definitely keep up the practice on the simple volumes, they'll take you a long way!
A specific piece of advice I have is making sure that the cylinders have a similar curve on each end (#8 in particular is one where this is a little shakey). I think you could benefit from drawing the full two circles at each end of the cylinder to help you visualize them in 3D space for now!
Looking forward to seeing more of your work