Hello Allaya and Welcome to the SOG Forum!
Well, I have done some medium making and mixing and I believe that there is a lot of value in experimentation and testing materials and trying differing mixes.
That said, I think that if you are just starting out, it is more important to focus on your technique and basic materials first and worry about complex concoctions and experimentation later.
I personally believe that there are mediums available on the market like Gamblin's Galkyd, and Studio Product's Marogers that are great for any painter. If you can find a commercially available medium that you like, it greatly minimizes the chance of causing a kitchen fire by boiling oil A and adding resin B.
Check out
www.studioproducts.com. People on their forum mix a lot of things, but the commercial mediums and oils available for sale on the site are top notch.