how do I beat fox effectivley?
You can:
1) Work on combo game against Fox. He is a fastfaller, so he is susceptible to that.
2) Work on edge guarding game against Fox. He has a rather linear recovery, as lengthy as it travels. He also falls very quickly off stage. This is where a lot of characters like Marth, Shiek, and Pikachu go to net stocks.
3) Work on chain grabs. Fox is one of the easier characters to chain grab because of his well, fall speed and weight. I believe Ganondorf himself has a DThrow chain grab on Fox. You should look into it. My main also has two, and my character would get destroyed if I could not get the chain grab going.