There’s nothing to be afraid of if you take your time, learn the techniques well, get educated on basics of anatomy and physiology and don’t do anything crazy.
The best way to approach (after a short period conditioning of your tissues) is two start with the least amount of manual routine that gets you some results. As long as it is working don’t add anything. Once you start to plateau on gains (or don’t notice any after a consistent effort over a couple of months) then you can start to increase time, intensity or training methods, or some combination of those. Then, again, once you are making progress keep it as simple as possible while you are making gains and don’t add anything.
The best advice for a newbie is to keep an accurate record of your training and measurements. Upload your stats to this website and update them on a regular basis. Years from now you can access them and see where you’ve been, even after a long break. Make a spreadsheet of your training and measurements for yourself.
Some guys track elongation, strain, increased circumference for each workout to see if their routine is effective, also great for a spreadsheet. This is more advanced but once your newbie gains start to slow is an effective way to see if you are giving yourself enough intensity and what seems to work the best, and when there is a diminishing return with more work, or even negative returns from too much intensity.
It also helps to show when things start slowing down so you can either increase effort (time, resistance, number of sessions) or even if it is time to take a break and let your tissues soften up. This is called a deconditioning (decon) break and many feel it is a great way to restart gains once you’ve hit a wall. Some guys plan for breaks of a week or two every couple of months, some guys throw in a break of much longer to let themselves return to some degree of newbie gains again.
So close tracking is really helpful once you are out of the newbie phase. You can wait until you are more advanced or you can start tracking now if that is the kind of thing that you like to do.
Finally, just like with any kind of physical training, it is fairly likely that you will have an occasional minor injury. Like a small bruise or blister from pumping or vacuum hanging attachment, or a couple of days of diminished erectile quality or sensitivity from overdoing your training a bit. These aren’t a big deal and are part of learning what works for you and how to train to minimize them. Nothing to be afraid of. It’s like getting blisters on your fingers from doing heavy yard work or twinging your knee while out playing football.
The likelihood of causing an injury that results in long term sexual dysfunction is essentially zero if you are doing normal stuff. In fact most guys find their sexual function improves with PE.