What's Best Heat point for OVERCOOLING condition

There is no “best” point for anything in Chinese Medicine - except the best set of points that is for your individual patient at that time. With signs of dampness, you do, however, have to be careful to not use too strong tonifying points too quickly in the process. Clear dampness first, then tonify (generally). On the other hand if they are truly too weak, you have to be careful using damp clearing points, so you really have to know the patients case well. Moxibustion is often very important in this process. Either way, SP 9 is an important point for clearing dampness, and then acupuncture and/or moxibustion on points such as SP 3, ST 36, ST 40, CV 6, CV 12, LI 10, etc. depending on the patients overall diagnosis, history, diet, etc.