Get grounded in the room or place you are warding, and pick a point to start. If it's a room, I start in the ceiling corners. Imagine a brightly glowing, burning ball of energy growing there - again, it might be the color of your aura, a favorite color, a mix of colours or one chosen for a specific purpose. It may also not be a ball, but a protective symbol you like; a pentacle, or other symbol, a rune or bindrune, or anything else you think is appropriate. These corner energy balls are the anchor points of your warding.
When you have anchored the corners, send energy out from one anchor point into the next, in a line - I visualize my lines as a braided cord of power, but yours might be a burning line of fire, or levinbolts crackling between corners. Some of my wards are done in Ogham; I visualize the "line" as a string of Ogham characters, done in vines. Whatever is most appropriate to your purpose is the best. These are the boundary lines - they define the boundary of your ward.
When you have finished setting the frameworks of your wards, meaning each corner has a strong anchoring point and each boundary line is strong, envision sheets of energy sliding down the wall. These should be flexible and strong, like the walls of your aura shield, and may be of any construction you desire. As you visualize the walls of the ward going up, give them intent - project your will for these walls as you would with your own personal shield. That can be protection from negative entities and energies, allowing in only positive energies, and keeping out uninvited visitors. Wards are as simple or as complex as you want to make them.