In regard to Yohimbine, which I find super effective, titrate the dosage up slowly as tolerated. Since they are usually in 2.5mg caps, start off with that, then bump it up to 5mg, then 7.5mg....and so on. Everybody's tolerance will vary. I'd only use HCL standardized versions because some of the other Yohimbane alkaloids can have harsh stimulation and sides with not much leaning toward thermogenesis. I've not looked into them in many years, but it was the case many years back when i looked into them.
Lyle McDonald has written about using a beta blocker like propanolol or metaprolol as it will ward off a lot of the side effects caused by yohimbine, while also burning fat via Atrial Natriuretic Peptide (ANP).