A lot of it depends on the kind of gun you are carrying and the way you intend to carry it. Since I'm guessing based off of
this thread you don't even know what kind of gun you want, what kind of holster, and so forth, it's pretty hard to say whether you will need to change or not.
But really, here's the deal. You just have to do it an see what works for you. You can take two guys with identical builds, identical guns, identical holsters, and identical wardrobes and the gun will disppear on one guy and on the other guy will look like he's smuggling a lead brick around.
The only "'I wish someone had told me this before I started carrying'-type advice" I think anyone can fairly give you is that this is terribly subjective and personal decision and there are almost no "one size fits all" solutions.
It really is one of those things that comes together much easier by doing rather than discussing. No one here knows what will work for you. Some folks here can slip a full size double-stack pistol in an IWB with jeans and think it's as comfortable as going around in sweat pants. Others find a P3AT in the pocket of pair a baggy pants to be cumbersome. Some of the people who dish out carrying advice here are years away from being old enough to buy a long gun, let alone carry a handgun. Without a bit of your own experience, it's hard to filter out what will be helpful to you.
I would recommend to not fret about it so much and to accept the fact that you may not get it right the first time. With enough work, almost anyone can find something that will work with either the gun they want to carry or clothes they want to wear. Sometimes these aren't the same thing. I will say that from my experience that people who select a gun/carry method that fits their lifestyle seem to stick with it longer and more often that those who pick the ultimate gun then try to fit their life and wardrobe around it.
Hope that helps.