It's never too early to think about monitoring and metrics. In my opinion you should collect metrics on everything you can think of: 1) How long does it take f

It's never too early to think about monitoring and metrics. In my opinion you should collect metrics on everything you can think of: 1) How long does it take for my page to load? 2) How long is this database query taking? 3) How long does this API call take? 4) How much storage am I using? et cetera. Your metrics should give you keen insight into common system metrics as well as application level metrics. Your metrics should show you your trends and tell you when you need to add capacity and / or improve performance. Cloudkick (http://cloudkick.com http://cloudkick.com) is doing (among other things) a lot to make not only metrics collection but monitoring simple. I'd check them out.