i used clean in spring, i just used it for 5 weeks straight, on week 3 i took dyphenhydramine every night before bed, this repairs your receptors, and i actually noticed it work, about 3 days after i started i got the shakes again so the clen was obviously working better now. i got alotta info off bb.com but also some good stuff here.
http://www.steroid.com/Clenbuterol.php drink TONS of water, and supplement taurine and potasium.