The safest in my opinion is :
daily pumping for no more than 10 minutes @ a pressure of 5-6 gh. You need a quality pump with a pressure gauge.
Get erect,lube up , pump to 5-6 gh and watch adult entertainment to keep it hard through the 10 minutes. Thats it, nothing safer than this. Jelqing, clamping, squeezeing is ALWAY application of uneven pressure. Your dick was never made for something like that. It was meant to be stuck in a vagina, and a vagina equals evenly spread pressure.
With his routine you will be on the safest possible side of Penis Enlargement, however prepare to see permanent results only after many month, like 6-8 month of daily 10 min. pumping.
Actually who cares, if you will be permanently 1" bigger in girth after a year or maybe a year and half, what else can you ask for ???
Sure , there are better techniques that lead to quicker and bigger gains, yet they always come with HUGE risks, that I would never take again nor advise to anyone.