Pocket squares, like the tie bar, are another one of those finishing touches that you don't see too much of. If you haven't worn one before, give it a shot and see if you like it. Here are a few tips on how to wear the square:
1. Don't wear a matching tie/pocket square combo. Never ever.
2. Don't try to get crazy with it. I wouldn't use a multi-peaked or puffed look personally, I know some that do and I don't dislike it per se but it's not my look.
3. Use a solid color--probably white--in a simple cotton or linen. There is some utility to the pocket square: It's basically a handkerchief in your pocket. If you wouldn't blow your nose with it if you needed to, it's probably too fancy. Silk ones (usually worn puffy) can be over the top, and they definitely have no utility. Most of the people I see wearing something in their jacket pocket fit into the silky/puffy category. The simple white square is a classic look, but as you can see in the pictures, it's also modern when coupled with a streamlined suit. You can get work stripes or patterns in if you dare.
4. To achieve the perfect fold for your pocket square.... fold it and put it in your pocket. Not complicated. Just make it so the uneven edges are in your pocket and not showing. If you want it looking really crisp, you could iron and starch it. Ironing a hankie is easy, and it's easy to wash
afterwards. Iron it, wear it, blow your nose into it if you need to, wash it. Repeat.