Need help, below 20k 9x9

I added a variation of some places where I think I could of made a better move. Would you agree with my variations?

Hi,

I posted another variation that would be a better move. The move you suggest has a big problem: white can separate that stone from the rest of the black stones, leaving it isolated and weak. I suggest you read this great article, the concepts in it are very fundamental: http://senseis.xmp.net/?LameDuGo