- Small pack - You can go as small as a fanny pack or as big as something like a pack used for school books. You don't need to bring anything bigger than that. Technical packs might be able to pack more gear, but you aren't going to need to bring anywhere near that amount of gear for a day hike.
- Hiking Boots/Shoes - Depending upon the terrain, not necessarily mandatory, but excellent to have none the less. If you're just starting out and don't want to shell out $100 on a pair of hiking boots from a chain store, check out Walmart's shoe section. They'll be just fine for any of your day hikes.
- Water - Keep with the rule of drinking 64 fl oz's a day, if it's hot out, pack some extra water. Each individual is different in their water consumption, but to be safe, for a day trip, bring about 2 liters of water.
- Food - Trail snacks are always welcome. Things like granola bars, dried fruit, nuts, even cereal will be great for a quick snack while on the trail. You want to pack fairly light so don't go overboard with the snacks. I also like to bring a sandwich to eat when I'm halfway through the hike, or at the summit of a mountain.
- Rain gear - A small poncho will do just fine. It's better to be safe than sorry so bring one regardless of whether or not the forecast calls for rain. You can grab a very light poncho at walmart. If all else fails, a trash bag will do a decent job of keeping you dry.
- Flashlight - On the same note as the gear. You want to be safe, not sorry. You may not be planning to hike after the sun sets, but if you take a wrong turn and get lost, a flashlight will be invaluable when night falls.
- Compass and Trail Map - You can find trail maps on the web and learning how to use a compass is never a bad idea. By bringing these, if you ever get lost, you can use them to get you going in the right direction.
- Fleece Jacket and Long Pants - If you're hiking in New England, you need to expect the worst. On Mount Washington, the tallest mountain in the Northeast, temperatures can drop to below 30 at the summit of the mountain overnight. By bringing some warm gear, you'll be prepared if you get stuck in it.
- First Aid Kit - A small first aid kit will do just fine. A few aspirins, some bandages, and some moleskin would be just fine for a day hike. You can either make one yourself or buy one from a sporting goods store. By making it yourself, you'll be able to customize it to suit your needs depending upon where you are hiking.
The best part about this gear is you can find it all fairly cheap. When I first got into it last summer, I went out to walmart, I picked up a pack for $15, some hiking shoes for $30, a compass for $3, I made my own first aid kit, and just packed a sweatshirt and long wind pants. That gear I bought I still use today when I go on hikes I'm very familiar with. I've even used the shoes in the White Mountains and I was fine.
The most important thing to remember is to be smart about the hike. Don't think just because it's a trail that's in your backyard or something that nothing can't happen. Things can always go wrong, no matter where you're hiking. As long as your safe and responsible, hiking can and will be an exciting experience. You'll get to see things you never thought you would see.