Here's how I make mine.
I like 1 gram of JWH-018 to 15 grams of plant matter. This is quiet potent for most people, a joint will absolutely head-fuck people without tolerance. I really suggest you go much lower for your first trial, maybe 300mg to 10 grams.
Also, just smoked JWH-018 for the first time in 2 days today. Tolerance certainly has lowered, but I still vape/smoke the same amount without any nasty side effects, I just get higher. I'm going to say a 5 day break would do a good deal to your tolerance towards this stuff.
Will report on JWH-250 tomorrow (compared to JWH-018, as that is my personal favorite by far).