The advantage of your K1000 and the reason why it has been the favorite of photography instructors for several decades is that it is both simple and complete. It has an accurate (center-weighted) TTL meter, decent viewfinder, fully manual controls, a good range of shutter speeds, and supports widely available interchangeable lenses. Most (all?) of the K1000's secrets are in the user manual.* Everything else (aperture, shutter speed, film choice, lens choice, composition, etc.) is basic photography and applies to all cameras, regardless of their sophistication.
Have fun and welcome to the Pentax Forums!
Steve
* Freely available for download (donation appreciated) at the Butkus site:
http://www.butkus.org/chinon/pentax/pentax_k1000/pentax_k1000.htm