Go rent a 9mm, .40, and a .45 and see what you think. Typically for new shooters the .40 is the hardest to handle. It is snappier with a more pronounced muzzle flip that makes follow up shots more difficult. The .45 has more of a lateral shove. The 9mm is by far the easiest to handle. For a CCW for a new shooter I would go with a Glock 26. 9mm being easier to handle, and most importantly cheaper to feed. For a new shooter you need lots and lots of trigger time. Size is very easy to conceal, it's not the smallest thing out there but isn't an issue. I CCW a Glock 27 off-duty and it's not a problem with a quality IWB holster. I personally use a Comp-Tech M-TAC. The S&W M&P 9C with no safeties would be my second choice. The XD's would also be a fine choice reliability wise, I just hate the damn safeties.
Now if it was a dedicated CCW piece and not doubling as a home defense weapon then I would take a serious look at a wheel gun.
It doesn't matter if you are shooting a 9mm or 45, if you shoot the bad guy in the leg instead of center mass you are still screwed. Shot placement is more important than caliber. Reason I like Glocks is they as reliable as anything out there and there is no safety. In the heat of the moment you don't need to be trying to flip off a safety, don't even get me started on grip safeties.
Open carry is retarded. Only reason I will accept open carry is if your state doesn't allow CCW, then I am OK with it. It does nothing to deter crime. If your OCing in areas with real crime then you are just making yourself a target. It doesn't make the news but people get jacked of their open carry piece more than you would think.
Open carry is CA is the most retarded thing ever. Open carry an unloaded weapon, what the hell is the point?
Second the MTAC recommendation, works beautifully on my Kahr PM45.
http://www.comp-tac.com/product_info.php?products_id=95
Viper GTS