Firstly I fold in the seam allowances on one side like this:
I fold them in tightly and crease them so the excess sticks up straight. Then I lay my scissors flat on the table and cut across the sticking-up bit:
That leaves you with a nicely mitred corner:
(It usually leaves a a little too much fabric at the point, which you then trim off in the next step.)
Then you just trim the second side to match, shaving a tiny bit extra at the point, and you're done. When the collar is pressed (which is a million times easier if you have a point presser) and turned through it should sit perfectly smooth and flat. Easy to do and never fails!
This collar is on this shirt. I cut this one out ages ago, but never sewed it up because I was a bit iffy about the proper two piece collar. And of course once I made it up I really liked it. The collar IS pretty snug. It does go around Nicholas' neck, but there's not a lot of room! I suspect it'll be worn open anyway, but I really like the look of the two piece collar so I think I'll enlarge the neck opening and draft a bigger collar.
I had to go into Miracle today (I get my flushable nappy liners there, so I'm in there fairly often!) so I dropped off my latest creations and asked Harriet (one of the lovely ladies who works there - owns the shop I think) what she thought of the pink top I made to go under the pale tunic and whether she thought my other idea of the white top would have been better. She liked the pink, so there you go. Judging by the choice of stock in the store I trust their judgement. She said that there had been comments on my stuff, but no sales yet. (Which doesn't surprise me - I'd have been stunned if anything had sold this fast!) My stuff is in it's own little alcove on white wooden hangers and it gave me a real kick to see it hanging there all cute and nicely displayed.