The first thing you need to know is that a ward is not consciously maintained. Rather, when casting a ward you must determine where it is going to get the energy to remain up. Common sources of energy are ambient energy, the earth, the sun, the moon, or even those who trigger the effect (common when casting a ward against those with malicious intent). The easiest way Ive found to tie a ward to absorb energy to stay charged is to use a personal symbol you associate with energy absorption and tie it to the main ward to feed it.
The second thing to consider when creating a ward is the shape. Common types are dome, sphere, perimeter, wall, and personal.
Dome and sphere wards are used to cover the desired area and either causes an effect within the barrier, or acts as a shield. The dome shield is open on the bottom, but is less energy intensive than the sphere, which doesnt have that weakness. Alternatively, if you desired, you could cast two dome shields to get a sphere effect, though the two wards wont be seamlessly connected as with a sphere shape.
Perimeter wards are set up like a set of four walls or a cylinder around the desired area. While open on the top and bottom, it is useful for setting a barrier around the walls of a room.
Wall wards are fairly two dimensional, having corners to mark the edge of the ward. These are generally used to set a ward on a doorway, such as a defense against those with malicious intent.
Personal wards are a bit tricky. They are tied either to a part or parts of your body or to an object you carry. This allows the ward to move with you while retaining the necessary anchor. There are other shapes you can use, but these are the ones I have experience using.
After you have chosen a shape and know how you are going to keep it maintained, you need to determine what you want to do with it. Common types are elemental, warning, vampiric, barrier, or a combination thereof.
Elemental wards can fall into two categories; offensive and defensive. Keep in mind that when you cast the ward, you need to determine what triggers it. An offensive ward is one such as a fire ward used to weaken and damage those who pass the line with malicious intent. It is designed to damage and harm those who trigger it. Be very careful when designing the trigger for any offensive ward, as if you mess it up, you can trigger it yourself.
Warning wards are just that, a warning. They let you know when something passes them. Oftentimes this is used to warn you when a spirit enters the space. This type of ward has to be tied to you in some fashion or it cannot send you the warning.
Vampiric wards are any ward designed to absorb energy from those who trigger them. Looking to the offensive fire ward I mentioned, I personally prefer to add a vampiric effect to it so it not only burns those who intend to harm, but absorbs their energy to make the ward stronger.
Barrier wards are any ward designed to stop something from crossing it. While usually ineffective against humans, they are useful for keeping spirits out of an area. This is the one ward mentioned here that I have no practical experience with, and you should be sure to understand spirits before attempting this.
The third thing you need to decide is the trigger. You know how the ward is shaped and what it does, but you also need to decide the conditions in which the ward is activated. If you dont do this, wards tend to either never activate or to activate whenever something or someone (including you) crosses it.
The final step in creating the ward is to put it all together. As an example, Ill walk you through the creation of a vampiric elemental wall ward. For the energy, the vampiric effect takes care of that, though I prefer to also have it absorb ambient energy in case nobody trips the ward. The shape is a wall, with four points, one at each corner of a doorway.
Gather your energy, and then trace the door frame with your fingers, concentrating on the trigger, in this case those with malicious intent. Focus on the feeling you get from such people, so that the ward understands what it is looking for. After the frame has been traced, spread the energy between the four points to create the wall shape. Now you have to change the energy to be more like fire. Once the ward is burning, concentrate on making the fire feed off of those who trip the ward with malicious intent. While concentrating on the effects, you need to tie the ward to a symbol you associate with gathering energy. By tying it to the symbol, the ward both becomes longer lasting and no longer requires your active intervention to prevent its collapse.
Be sure to not lose focus on any part until the ward is tied to the symbol, as it can collapse or even backfire. Please try a few simple wards before trying anything that is offensive, as a backfire from an offensive ward tends to be worse than any other kind.