You need to have a plan before you go out. Decide where you're going to go and learn about the area. Make sure you understand the rules and regulations of the area. In some spots you cÐ°n't light fires for example because there are bans. You should create a list and decide what you want to take in your pack. Make sure you have a good map of the area and don't rely on your cellphone because some areas don't get good reception or none at all. A paper map of the area is essential. Make sure you know the roads in and out and get a good compass too.
Get in Shape
Before you do serious backpacking you'll need to be in decent shape. Start with long walks along trails without weight and then add weight to pack and go out for day trips. Once you do this for a while your body will adapt and you will be set for longer trips. Make sure you stick to easier hikes before you venture off into other terrain because it's easy to get lost of injured if you're not prepared for the hike.
Many backpackers make the mistake of bringing far too much gear with them. Everything you add just weighs down your pack and your back more so plan to pack light. One thing you should do is to pack a lighter tent. You don't need a giant tent for backpacking you want one that is going to be light and easy to setup as well as pack away. Make sure you buy a decent pack that can hold all you gear and one that fits comfortably for you. It's best to try out the pack before you buy it.
In the wilderness you need to stay safe. Water is your most important resource so make sure you have enough and be sure to drink a lot as you hike. Stop at streams and lakes to fill up and be sure to decontaminate your water before you drink it. Understand the wildlife in the area and be sure you have bear spray with you but only use this in an absolute emergency. Your pack should have a medical kits and tell your friends where you will be going and when you expect to be home. Take a cellphone with you for added security. Another thing to ensure you have is proper hiking shoes or boots. Never hike in runners or other shoes as you will quickly fatigue your feet and get blisters.