If your looking to learn more about buffer overflows, maybe because your studying for your OSCP exam, here are some resources I've found to be helpful.
Right now - one of the most helpful resources is the THM room below. It has lots of details, explanations, and enough practice to build muscle memory for the exam. The room's free, too.
Above is Tib3rius's YouTube walk-through of the BOF room on THM. Very useful.
Often recommended, Adams BOF made easy. I haven't personally used it - but it's commonly referenced.
Dostackbufferoverflowgood - created in 2016 for a talk at Crikeycon. Covers basic assembly, registers, the stack, overwrites, etc.
HTB Academy's learning module for Windows x86 BOF.
Lastly - try to build a network of friends who you can collaborate with. The hands on, interactive nature will be extremely beneficial.