One of Batman's strongest traits, be it a flaw or a virtue or some blending thereof, is his relentless obsessiveness. It isolates him from normal people, making him something of a grim misanthrope. It is also from there that he gets his drive to stand against the cowardly, superstitious parade of criminals that threaten the peace and his desire to achieve justice at any cost. Of course, when you're a multi-billionaire, "at any cost" is afforded a high ceiling that can cover a lot of obsession. An obsessed, wealthy, misanthropic loner with an open-ended mission naturally makes up a few rules for himself to fill in the gaps left by the rules of society he has chosen not to follow.
- If you break it, buy a new one. It may seem distracting sometimes, but cleaning up after himself keeps his own things properly maintained and promotes public goodwill when he replaces their firebombed cars and such. Either way, it helps him continue his crusade.
- If bad guys break it, break them. That falls right in line with his war on crime, so he hardly considers it a distraction.
- Be prepared. The endless arsenal of useful gear isn't just for show.
- Not announcing your comings and goings makes people nervous. This keeps people spooked, never sure when he'll be wherever he is, which is great for a protagonist who likes to gather intel from dark places and shadowy people.
- Don't hesitate to be mysterious. Not answering every question and leaving people to use their imaginations has an effect on other characters and readers alike. It should make an impression on all of them and make at least some nervous.
- Make people nervous. I'm not saying that clothes alone make the man, but black looks cool on good guys, too. Combined with the whole "mysterious loner" thing...
- Don't play well with others. He is a misanthrope after all, so it's really going to have to fall to others to play well with him, isn't it? Who doesn't like a protag who's strong enough to set his own terms?
- Win hard. Again, it makes an impression.
- Never let them see you sweat...or smile...or laugh... Never let them see your eyes either. When possible, never let them see you. It's a guy thing. In the right places, it has its uses. More generally, referring back to Sun Tzu, don't let others know you (or really see you) and you'll retain a big edge toward attaining victory. This makes the unknowable character appear to have a formidable strength.