Day1 of a new amazon review site - feedback on results and next steps

So, I spent a couple of days setting up a niche review site with about 20 reviews on a niche in electronics. The reason isn't just for making money but also to improve my own skills when it comes to PPC and analysing/tweaking data.

I launched the site yesterday using adcenter as my traffic source. Now, it's kind of hard to to the exact analysis here because I'm not sure wether amazon and adcenter follow the same 24 hour segments, but I'll base this on the fact that they do.

Yesterday I used 11$ with adcenter (out of a small 20$ budget, started late in the day, will use up all of the 20$ today so budget could be bigger but I'm taking it slow).
Result: 5 items ordered for a total of 400$. Now that's a couple of dollars in profit but the main thing is, people actually ordered something.
Also had 2 signups for a newsletter but the form is badly place
The issue I have is of course that I'm not able to track what keywords convert in amazon. So, what I've done now is just track all keywords that exit to amazon as those are the ones that will (most likely) make me money.

Any other/better ways of tracking conversions? Any suggestions to what I've written so far? All help greatly appreciated