As an exhibitionist myself, I have a hard time saying this, but from what I see, the two main pitfalls of amateur pornography (including solo exhibitionists) appear to result from the desire to exhibit oneself overcoming any and all considerations for taste or aesthetics.
The first of the two pitfalls on my mind is the belief that people want to see lots of closeups of genitals. I'm willing to believe this is a matter of taste, but if you ask me, the genitals aren't usually the prettiest parts of a person's body. Yes, they carry a strong sexual charge, and in the right context, with appropriate consideration, they can be a potent and even central element of an erotic portrait. But, though it might be exciting to put your private parts out there on display for all the world to see (believe me, I understand - though I think in a saner world, less censorship of those parts in general would reduce the arbitrary thrill of exposing them), it's usually not something a lot of people enjoy looking at.
Again, I'm not saying genitals have no place in an erotic portrait. I'm just saying that an erotic portrait is far more interesting to look at than an anatomical closeup of some stranger's private parts.
The second of the two pitfalls is not unrelated to the first, and it deals with the single-minded exhibitionist's complete disregard for the principle of scaled beauty. That is to say, the fact that not everyone is equally attractive. Some people are prettier than others. A hot girl might be able to get away with posting a bunch of pictures of her snatch, but how many people are interested in seeing a fat man's cock from dozens of angles? Again, maybe it's a matter of taste, but if you're not especially attractive, the chance that people are going to want to look at you drops significantly.
I know, it sounds kinda harsh. But that's the truth about beauty. If you don't have it, it doesn't mean you're a bad person, just that you should try to find something else you're good at, and leave it to the pretty people to cover the modeling gigs. And I know, as an exhibitionist myself, I understand that it's not entirely fair to say that you can't enjoy the thrills of exhibitionism if you're not lucky enough to be attractive. I don't exactly know what to tell ya. I'm not gonna say "give it up", because if I hadn't gone out on a limb years ago, I wouldn't be where I am today. But then, exhibitionist though I am, my goal was never simply to get my jollies from flashing my naughty bits in front of (expecting) strangers, I actually had a passion for erotic pictures. And A desire to make good ones. Getting an exhibitionist thrill out of practicing my craft was merely a job perk that provided some extra motivation to continue.
I'm tempted to say that, even the ugliest subject can make a few adjustments to improve a portrait. In that case it comes down to how much effort you're putting into it. If you're snapping a shot just to get it up there to reap the illicit thrill of shocking (and possibly disgusting) others, well, that tends to show. On the other hand, you might take the time to take a shot that looks better, or even weaves some interesting elements in, perhaps even approaching the realm of art. Of course, it takes some creativity and experience, but you might as well give it a shot. After all, if you can make a good portrait that people will actually like (and not only because it's dirty), that you can still get an exhibitionist thrill off of, not only is it likely to be an even bigger hit, but then you can be a lot more proud (instead of ashamed) of it later on down the line!
Just so we're clear, I have no interest in censoring whatever it is you'd like to express yourself with. I'm merely encouraging you to reach down and pull out your greater potential. I encourage everyone to experiment, and trial and error inevitably leads to a number of misses - by all means, not everything you produce will be a gem. But if you push yourself for better results, the average quality of work available overall will improve. And who knows what you might be able to achieve! :-)