i went out to fly today with wind speeds according to the news and online at 10-15mph. at first i was able to fly okay but it after a few minutes i couldn't get the kite to stay up.. it seemed like the wind was changing directions i'm not sure if it was me or the wind. any tips?

Were you flying in a nice clear area with no obstruction for a couple hundred yards? Wind can get really messed up around trees and buildings. If I get too close to a stand of trees in my paddock the kite luffs and falls out of the sky and I basically have to pick it up and walk it well clear of said trees.

Failing that, check the bridles for any snags - I often get them on my depowers, not so much the fixed bridles.

I 2nd what John said. Upwind obstructions are huge! If the wind is swirling you are going to have trouble. One day I was flying fairly close to houses. Left side of the window....no problem. Right side and bedsheet time.
A 100 yds down wind of most houses should be adequate. Also, themally generated winds due to local instability are going to be difficult to fly in. If you are on land and see alot of cumulus clouds in the sky...beware.

Downwind obstructions can be bad too ...

alright makes sensee.. the one time i was flying kinda close to trees the other i was flying in a soccer feild so im not sure about that maybe just a bad day?

Have a look at page 9 on this PDF - one of the best illustrations of how and where to fly powerkites I have come across

http://www.powerkites.de/images/stories/manuals/quadline_pow...