Hind sight is 20/20 it has taken me a long time to let that feeling of "I could have got it cheaper" go. I like to throw in a low bid and go for a walk. 9 times outta 10 I get a nice surprise upon my return.
Then if it goes south I just do it again. Try not to buy in large lots, the commission is a small price to pay to break your buys up over a few days.
But always bid low...you never know. Another rule I learned is never chase a stock...If you are patient it will come to you.
JMHO I used to take alot personally and I think I finally have learned some patience.