You can always change the specific plan if you stick with the same provider, if you discover that the way you are currently set up is costing you more than you would like. They'll be happy to do it at no charge if this means you're keeping them as a provider.

Backup you phone numbers TO THE SIM CARD on your phone. That way if your phone breaks you just transfer the card to the new one. If you are prone to losing your phone (being strapped for cash hopefully you're welded it to your wrist to prevent such a costly mishap :P) get an extra SIM.