Location
You obviously need to know where you're going. You pick out the area you will be hiking in and maybe even the trails. When you know for sure where you're going and how long you will be there, you really should tell someone so if anything is to happen, you can be found. A part of planning the trip is knowing what routes to take and determining how long you will be gone. If you are wilderness hiking where all your directions are based on navigational skills and use of a topo map, you need to determine the best routes to fit the level of difficulty you want. Also take into consideration of the xperience of the other hikers in your party. Try to plan the route that is most appropriate for the level of the least experienced person.
Food
When you determine how far you are going to trek and how long you will be gone, it's time to plan your food accordingly. Take into consideration how much food you normally eat for each meal then add up how many meals you will have. You can also take the easier route of having dehydrated dinners for each meal. Decide what kind of food you want to bring and make sure you have the means to prepare it.
While determining the length of the trip, also consider the route and how many water sources are along the way. If there won't be many water sources, bring extra water. If you know there will be plenty of water sources, you may only bring the amount of water you need for hiking. Also remember that when winter hiking, you can melt snow.
Clothing
As you begin to plan the trip, start looking at the forecast and what the weather will be like. If it will be damp or rainy, you may want your good rain jacket and pack cover with a spare poncho. If it will be cold or snowy, you will want your warm clothes. Also take into affect, the weather at night. Do you need the 30 degree sleeping bag or the -10. If you like to sit around the fire at night, you may need an extra sweatshirt. Make sure to have clothing appropriate to the climate and temperature. Even if the forecast looks good, you may want to bring a little extra if you will be in an area with a certain climate. For example, you trek in Alaska and the forecast shows sunny and clear, but you know that it tends to get cold and rain a lot, so you take light rain gear and extra insulation.
Camping
If you are hiking a trail at a state or national forest, there will more than likely be campsites along the trail that are already made up. However, if wilderness camping or camping where there's no premade campsite, you should plan your set up. Take into consideration how long it takes you to set up shelter, dig a latrine, dig a fire pit, make or set up chairs, and so on. Think about how long it takes to fix your meals and if you want to day hike a little after getting to camp, factor that time in. When you determine how much time it will take to set up camp, you can figure how far and long you should hike before stopping to set up.
You also need to decide what kind of shelter you want to bring. Most people go with tents, but you may want to just sleep under the stars. You may want the hammock, snow shelter, or just tarp camp. Your shelter will be relative based on your preference and type of weather and terrain.
Travel party
Probably the first thing you may have planned is your traveling party. How many people will be going with you? After you decide, you really should work together to even out the load. Maybe someone can haul the tent while someone hauls food and the other carries cookware. The trip will be much more pleasant if everyone shares the load. You may also want to determine everyone's roles. You saw in one of my last posts that the trek can be much easier if everyone splits up responsibilities. Someone is the medic while someone is the navigator. Generally, the one planning and coordinating the trip ends up being the leader.
Make sure to plan your trip well. The better you plan the trek, the less "bugs" you will have and the experience can be much more fun. If you will be hiking with more than just yourself, try to involve the others in the planning process. Comment below what you think.
