Getting attacked can suck, but luckily if 40% of your town is destroyed, or your Town Hall comes crumbling down, you’ll have a 12-hour shield. If 90% of your base is wiped out, you’ll get an extra four hours. How do you best make use of this time? Well, don’t go out and start attacking right away, that’s for sure. That will cancel out your shield immediately.
The safety time is valuable, so use it to your advantage - take some time to figure out how you can improve your economy, build up your army, upgrade towers (since they don’t fire when upgrading) or simply stockpile and spend resources before the pain train comes rolling around again. Shields are useful enough that you may even want to voluntarily move your town hall out into the open; you'll lose trophies and some resources, but often the amount of safety time you get out of it is worth it. If you get really itchy for battle, remember that Clan Wars don't affect your shield timers at all.