The easiest way to pass is to not do drugs.
The next easiest is to take drugs which pass from your system somewhat quickly and don’t leave a lot of residue. Unfortunately, this is frequently the harder drugs.
The third option is to take drugs which are very recently designed and so are less likely to be tested for. This also means one has more danger of side effects and other issues. A major step in understanding how Parkinson’s disease works was when a new synthetic heroin gave a version of the disease to young people.