I love estiming, I do it a few times a week. I am not into estim pain at all, nothing like that, but I do like a good estim. Sometimes, I end up a session with the P.E.S. box cranked all the way up, and that's enough for me.
One trick, hard to do, is to not crank the setting up too high too quickly, because your body adjusts to the higher setting and you don't (at least me) feel it as much. I can do HFO once every few days or so with a P.E.S. prostate simulator, a ring around the end of my cock just behind the glans and a P.E.S. box. It's best for me to let the cum build up a couple of days, that makes the session hotter. I also like ghost fucking a lot and slowly jerking off, sometimes with my legs up in the air in front of a large wall mirror so I can watch the entire session. I get really good thrusting action with ghost fucking.
I have the settings marked on my P.E.S. box where HFO occurs and I slowly work my way up to that. Also, I love nipple play, so, I sit on the toilet, lid down, connected to my P.E.S. box and play with my tits, tickling, pinching and sometimes large binder clips on my tits which I gradually pull on as they slide out to the end of my tits, or sometimes I keep reclamping the binder clips as I work my way to the end of my tits. I don't always use the binder clips, it makes me cum too quickly, usually I just tickle and play with them.
Sometimes, to me, with estim less is better. For example, anally, if you have a moderate setting and play with the frequency, your body/muscles will start interacting with the estim so your ass will pulse on its own a bit interacting with the pulsing in my case of the P.E.S. box. Sometimes that setting is hard to find. I tend to rush too much with estiming, but sometimes when I used moderate/low settings I can find that point and it's really cool. It's like a low level tickling, like someone poking you in the asshole/rectum a bit.
I also love ghost fucking with a Zeus large torpedo anal bipolar plug and my P.E.S. box. I have modified my plug some so that it can not fall out or get sucked in, that way I can position myself however I want and get an excellent ghost fucking. That, is not HFO. It feels so good!
Here is a link to my Zeus large torpedo anal bipolar plug and my P.E.S. box http://www.zity.biz/index.php?mx=forum;ox=display;topic=78320;start=msg558990#msg558990