Emphasis is to be placed on one's lifestyle more than the actual drugs themselves. One of the best harm reduction techniques is just taking care of yourself. If you can afford to spend money on drugs, then you can also spend money on healthy food and supplements to make sure you are staying well. Treat your skin well with the right beauty products and exercise too.
There are some drugs, however, that should be completely avoided, such as amphetamines, cocaine, and prescription stimulants. Such drugs really are age excelerants. There is no high that is worth damaging your body.
I take amp once in a while, and yes I do agree that they take a toll on your body. But you may be able to minimize the damage by keeping hydrated, getting your minerals, your sleep, taking antiox, follow a scheduled diet, etc. That way I can keep my skin clear even on amp, but I never take it for more than 1-3 days in a row. But, sadly, stimulants and uppers are probably the worst for your body, "metabolically" speaking.

