The keys to a good hike are being prepared with the right gear, having a trail route plan in advance, and knowing your limits.
Boots are key. Know what type of feet you have (pronator, supinator, or neutral, as well as low-volume, high-volume or regular volume feet) or get evaluated so that you know what type of boot will fit you best. Speaking from experience, this step alone will save you a lot of time and money on unsuccessful boot purchases. Consider shopping at a store like REI or Backcountry that has a more generous return policy.
Hiking poles are great, especially for longer hikes as well as hikes with steep downhills. They take a ton of load off of your knees. Black diamond and Lekki are the most popular brands.
Trail Route Planning
It’s always a good idea to bring a map with you (and a GPS if you have one). A ton of parks post their trail maps online, in downloadable PDF format. Know what trails you plan on taking, how many miles approximately you will be hiking, and how long you expect to hike for. If you’re going out on your own, of course, it’s best to tell someone else your plans (just in case!).
Know Your Limits
Hiking can be extremely fun but also quite taxing on the body at the same. Make sure your body is prepared to go the distance, however long it will be. Do plenty of shorter training hikes to get your body used to all the ascending and descending that you’ll often encounter on longer hikes. Obviously, the amount and distance of your training hikes all depends on what hike you’re preparing for (Ex. Yosemite’s 16.8 mile Half Dome vs a short 3-mile jaunt in the woods).