I would like some advice on knowing when to tack when going upwind in a race. I am not real clear on terms such as laylines and tacking angles. If the wind is at 10 mph, when would I tack, at what angle to the buoy?
You might want to get a racing strategy book. Generally, you minimize tacks as they do decrease your speed. So, in that case, you would sail all the way out to the layline and then tack and sail to the mark. The layline is the line to the next tack, which is going to depend on the conditions and your ability to point the boat. Going all the way to the layline is risky in shifting conditions, as you may get "headed" (wind shifts NOT in your favor), while someone that stays in the center of the course might get "lifted" and beat the pants off of you. Anyway, please don't flame me as this is a really complicated subject and the possibilities are numerous.
The tacking angle depends on the quality of your sails and the wind strength. With good racing sails and a strong breeze a Capri 14.2 should tack through about a 95 deg. angle. This means if the mark you're aiming for lies just aft of your beam, you should be able to lay it after you tack.
But with less than perfect sails, and a light to moderate wind, the tacking angle will be about 110 deg, which means you should tack when the target is about 20 deg aft of the beam.
Don't sail for the corners. The last post (above) got it right. Best to go up the middle and lay a short layline. When to make your tacks while going up the middle? If suddenly you're not pointing quite as high (relative to the compass or some landmark on shore) then you're being headed. Time to tack. For the reverse, if you find yourself pointing higher, you're being lifted, and should stay on that tack.