Budding photographer here, and I'd like to echo the feeling of my respected colleagues. I have a Praktica L, which uses M42 (AKA Pentax Screwmount) lenses, and I'm relishing the availability of good, cheap lenses. My body is fully manual, doesn't even have a meter, but I got it CLA'd so that the obvious defects are wiped out.

Honestly, when you begin, you can't even judge yet the effect of two different lenses of same focal length (I know I can't). Bear in mind that you have to figure out at the same time the problems of proper exposure, depth of field, and compostion: getting down and dirty with the details of how specific lenses look, how film reacts, how they combine with processing techniques, and how they look on paper will take you YEARS. Go incrementally.

Start by getting the obvious facts right: is my shutter accurate? is my light meter also accurate? can I take pictures without shaking? are my lenses clean? is my body light-tight?

Get a few cheap prime lenses (~30-50$) of decent brands, usually japanese (vivitar, pentax, yashica, asanuma; 50mm Zeiss can also be cheap) to get a feel of different focal length. It's the most obvious feature of a lens, and that will get you started. Don't try to make too fine distinctions too early because your eye will be looking at the wrong things.

For your first developments, any average lab will do. Find the one that's closest to your house, so you'll minimize on shoe costs The point is to see whether you're overexposing or underexposing, if you can find the right angle/focal length, and if you can focus. Don't even think of mastering contrasts yet, and think formally.

At that point getting to know a more experienced photographer and/or finding a lab that can process your film manually will become invaluable. The learning process is very individual, so being able to talk with someone and ask questions in terms YOU understand will bootstrap you into something more accurate. Start reading technical, artistic, and critical literature. Show your pictures around, and exchange ideas. Experiment with what you know. You'll be surprised by how much you can accomplish when you sit down and think hard instead of hunting gizmos.

Overall, you want to get manual control on more and more aspects of your work. This takes time, effort, and learning. There's no recipe.