Maybe the best advice is to start slow. If you are a complete tenderfoot, going on a 15 mile hike that bags three 4000 ft peaks is more likely to be a bad time than a three mile hike that summits once. Backpacking the 100 Mile Wilderness requires a little more planning and confidence in your gear and skills than an overnight where you have cell service throughout. Hiking on the east coast, where water is plentiful and you pretty much can't walk more than a day in a straight line without hitting a paved road, is a different beast than places out west where you can easily die of dehydration or bumble off and never be seen again.