Rick Simpson oil was developed decades ago, using rudimentary cannabis science and the equipment easiest available at the time. Originally, it was made using naptha and THC dominant cannabis. Nowadays, just about any non-smokeable cannabis extract made with ethanol can be called RSO, but generally it refers to the thick, black, THC goo, processed at high temps, used to treat cancer and other medical conditions. FECO, is fully extracted cannabis oil made with ethanol and is basically the same as RSO, but processed at much lower temperatures. Both of them tend to be about 65% cannabinoids, give or take, due to the fact that they “traditionally” contain lots of unfiltered waxes/lipids. FECO can contain CBD, THC, or any combo, while purists insist it must be THC heavy to be RSO. RSO typically connotes decarboxylation, while FECO can go either way, depending on use.
Some people insist it’s not RSO/FECO if you filter out those waxes/lipids, so super clean and filtered oil is usually referred to as CCO or concentrated cannabis oil. It can be derived many ways, but in my opinion ethanol is the easiest for the home mad-scientist. 
A clean ethanol extract can be upwards of 80% cannabinoids! Because of its purity, CCO can be smoked…and should taste amazing. It can be decarbed or not, depending on your use.
If you don’t want to get high, go for something like a 3:1 ratio of CBD:THC for sublingual dosing. The higher ratio of CBD will help minimize the psychotropic effects of THC, while still allowing you to benefit from THC’s medicinal effects. Here’s a guide to dosing:
Project CBD is a great all-around resource to check out!
For a topical treatment, CBD has been found in studies to reduce the size of tumors when applied to, and kept in near constant contact with, the tumor. Scientists say it works by cutting off the blood flow to the tumor. This is still being studied, but the results look promising.
You’ll want to familiarize yourself with these 4 terms/ideas to help you decide which strain is best for you:
Terpenes
Cannabinoids
Decarboxylation
Entourage Effect
Once you check out those terms, let us know what you think or if you have any questions. This is all very subjective. You can completely tailor this to fit your exact needs.