Should I get a left or a right holster?
If you shoot left handed, get a left handed holster. CC'ing is more than just having a firearm on your person. Drawing from concealment (and reholstering) are incredibly important skills that require practice and muscle memory. It is not efficient to draw right handed and transfer to the left, when LH holsters are available. Then, think about a reload drill. Where might a mag holder go? Fishing one out of a pocket can be pretty slow.
I think iwb is more concealed than owb.
Absolutely. The advantage of IWB is that the slide is concealed in the beltline. The bottom of the grip is typically the first thing to print with movement. The disadvantage is that most people need to buy bigger pants carry this way.
There is value in OWB, but there are more considerations in terms of gun size, concealment garment, carry location, and how to explain that goiter on your hip at 3:00 or 9:00.
materials. What’s your opinion about this?
Holster materials are personal preference. To me, the important part is: if I would ever have to actually use a CCW, can I reholster the firearm so that I'm not the guy holding a gun when the police arrive? Most IWB leather only holsters do not keep their shape well for reholstering. Fully Kydex holsters or Kydex shells with leather backer holsters keep that IWB space available for reholstering.
There's a million different opinions on where to carry....and many different body types. The preferences of some may not work for others. It depends on the size of the firearm, where a person wants to carry, clothing choices, etc.
A few other thoughts:
Any CCW carried for any length of time will not be a pristine firearm. Even polymer framed, nitrided firearms will show wear. It is part of CC'ing.
Any product with leather will take time to wear in. Kydex/leather hybrid holsters can take approximately 30+ days of daily wear to break in.
The proverbial drawer or shoebox full of holsters frequently comes up. A person is not relegated to that fate (and expense) if they choose carefully. Holsters multiply when people want to carry multiple guns, multiple ways. It does not have to be that way. Sure, a good belt, holster, and mag holder may cost $200 or more, but they may last you several years - they are wear items. Contentment saves a lot of money if you don't feel the need to always chase the latest and greatest.
A good belt makes all the difference. It ought to be at least 1.5" wide leather and have good fitment with the holster attachment, but does not have to be double layer leather with a stiffener. It's just that fashion belts found in department stores typically don't work well.
Lastly, expect your clothes to wear out faster. It's just part of it. Whether it's clip holes in your pants, belt loops coming off, holes in shirts, etc - metal always wins against fabric.