I spent a few rainy/snowy afternoons inside practicing a bunch of different knots just to get the hang of tying them. It was really helpful. If you have some spare time and some cheap monofilament sitting around, maybe practice tying.
My system is: nail knot a mono loop (surgeon's or perfection loop) to the fly line, then loop to loop connection (surgeon's or perfection loop) to connect my leader. Then triple surgeon's knot to add tippet to a leader when needed, and davy knot (really strong and simple knot!) or clinch knot to tie fly to tippet.
So basically I've learned 5-6 knots to do everything I routinely need to do. I also learned the no-slip mono loop for tying on streamers (gives them better action), and the blood knot (prettier looking line-to-line connections than the triple surgeon's knot).
Probably TMI at this point... sorry. You really do need to know at least a few knots. I have a pocket sized knot guide (http://amzn.to/14E87GF) that has been really helpful.