Start at 200mg caffeine and 25mg ephedrine each day and see how that feels for a few days. If all is good, bump that up to twice a day. Ultimately, keep bumping up the dosages ---- keeping it at no more than 1g of caffeine and 75mg of ephedrine is probably a good idea. You may not end up taking that much caffeine but that's fine, don't take more than you feel okay with.
Keep in mind, there's no point to this if you aren't certain that your diet is in order.