Not so much a tip but an observation.
Most smartphones these days will sync their time off the cellular network to which they are connected but sometimes they can be out of sync with the time on your computers which are set to sync against time servers out on the internet. If you work in an office environment this would explain why you might hear the calendar reminders all go off pretty much at the same time which the smartphone alerts will come in dribs and drabs around fifteen minutes prior to a given meeting.
Anyway, Windows Phone 8 appears to lack any native functionality to sync its time from a time server with automatic time retrieval from the connected cellular network. Apps cannot sync the time for you as the access required to perform that function is restricted which pretty much leaves you having to manually set the time against a known accurate clock.
Is this a big deal? Perhaps not for most people but for some where time is of the essence then this may be worth keeping in mind.