Before the nay-sayers get here...
What're you trying to accomplish? Trying to get people to ask you about it? Just doing it cause you can?
If you're doing it to draw any sort of attention, most of the time, people don't notice, or at the very least they'll keep it to themselves. I suggest reading all pertinent statutes on the legality of OC where you're going, then read it again. Bring copies in case the sheep get frisky and calls the police.
What time of day
Whenever. Depends on where you're going to be. If you're going to be outside, do it more when it's light out. I've OCd pretty much all hours.
what types of places to visit
Anywhere guns are allowed
how to talk to people
Um...normally...When I've been asked why I'm OCing, I usually just say "cause I can". If the convo dies then, fine, if they wanna keep talking about it, I just say how it's legal for me to do and I like expressing my right, kinda like if a cop asks to search your car, you CAN say no. Does it look suspicious? Maybe, but it's your right and you are allowed to express it.
what type of dress
First time I OC'd I was in a shirt/tie cause I attended the GRPC...since then, I just wear whatever. A "nicer" shirt (not necessarily a button-down but something presentable), jeans.
what type of holster
I carried my Ruger in a fobus and my Sig P6 in the duty holster that came with it. Carry it in something that's visible but accessible in case you need it.