You have to experiment to find what you like. Keep notes!Virginias (ribbon or cake): can be all of a blend.
Latakia: anywhere up to fifty percent. Twenty five to forty.
Turkish: more than twenty five percent is excessive. Twenty is good.
Burley: at twenty percent, it starts to become a Burley blend.
Perique: four or five percent is fine. More is risky, and sometimes insane.
Don't get too complex. Three to six different tobaccos, no more. Four or five is best. Don't overdo the condimentals lest they clash.
Most blends I like 40% Turkish and some of my VaPers I like 30% Perique. What works for me may not work for you.