i started at 20 and get to 60 and the side were too much for me, but everyone is different so just see how you respond. the half life is like 35 hours (some say 28) so the 2x a day would help keep the dose a bit more even.
I would do 2 weeks/2 off and use an eca - ephedrine - caffeine - aspirin stack during the 2 off and take the bendryl that 3rd week.
that said, i will never use Clenbuterol again, i like the short half life of albuterol (like 2.7 hours).