Where to start..fox is a very fast, with a lot of variety. Every attack is not wasted and can usually be used to chain into another move, so he racks up percents very fast. His edge guarding isn't too great but he still has an awesome back air, and a Nair for camping.
His approaches come in a large variety of dash grabs, dash attacks, nairs, pivot f-tilts/grabs, dash shielding, dairs, rar bair, and sometimes even fox illusion.
For beginners his approaches tend to follow simple aggression with these moves I stated above (which all chain up with more combos). Doing these moves is a good place to start off.
Combo wise his BnB consists of
- Dash attacks to U-tilts (10-50%). This can get someone to 50% with just this one combo.
- Down throw to Fair to Uair
- Down throw to Fair Spike to (anything really) *Note that the spike can be teched
- Jab, Jab, pause, Grab
- Nair to Up Smash (100%+ KO combo)
- F-Tilt to Up Smash (70%+)
*There are many more combos but these are to start you off
Once you learn how to combo and you start facing high level players things like spacing, cross-ups and reads become very significant and is where most people will begin to struggle with fox.
His defensive options come from spacing and shielding. Running up and shielding can bait out quite a few moves, and spacing become significant once your opponents begins to learn of what you are doing.
Every now and then you can throw in a roll, since this game gives you some leniency but don't plan on relying on it since rolls are still easily punishable.
Overall there is A LOT of content on this forum so all you need to do is just practice with him, I can't really tell you everything but once you develop your own playstyle you'll begin to develop things much further than what I've put on here.
EDIT: Forgot to mention his KO options. Experiment with his Smashes (his Usmash in particular), his Bair, and his Uair.