In the last month I have gotten back into listening to vinyl. I have found a "ton" of great albums by Herb Alpert and the TJB, Al Hirt, Maynard Ferguson, Doc Severinsen, etc. But many times, when you pick them up for a "buck", they are showing their age.
A good record cleaning brush (with solution) can do a decent job. But if the record is really dirty, it will usually only push the dirt around. While doing some research on the web I came across a cleaning technique that I tried as a kid back in the 1970's, and totally forgot about...but it does work great.
Put a couple drops of "Dawn" dishwashing liquid in a small bowl of warm (not hot) water. With a soft, lint-free cloth (dipped in the soapy solution) gently clean the record surface. Wipe in the direction of the grooves, in both directions...clockwise and counter-clockwise. Rinse the record thoroughly with warm (not hot) water.
Put a bath towel on a flat surface. Lay the record on one half of the towel, and fold the towel over on top of the record. Gently "pat" the record dry. This cleaning method works quite well. It will usually eliminate many "pops", occasionally repair a "skip" (because dirt has been dislodged), and restore low-end frequency response.
And once your vinyl is clean, you can get new sleeves at:
https://www.sleevetown.com/lp-sleeves-inner.shtml
I enjoy sharing things that work. All the best.