Misjudging the weight that the tripod has
In wedding photography, there will be instances wherein you will be mounting really lengthy lenses on your camera at some point or so (case in point is the telephoto lens). You need to make sure that you get to balance your tripod with weights in order to stop it from tipping over due to the imbalance caused by the length of the lenses that you use. The center of the tripod usually has a hook of some sort and you can use it to hang some weights on it to give it the kind of balance that it basically needs. A camera bag will do just fine in acting as a weight that you can hang from under the center of the tripod just to make sure that your gear does not end up crashing down to the ground.
Setting up the tripod in a beach
Wedding photography involves requiring you to shot in different kinds of locations that have their own sets of challenges at the end of the day. One of the most challenging locations for you to shoot in would have to be the beach. Do not make the mistake of setting your tripod up on the sand because it will only sink and you run the risk of getting the rest of your gear wet or getting sand on your camera as well (which is always a bad thing). If you are forced to have to be in this particular location and a tripod is absolutely necessary, you can put some “snow shoes” on the legs. They are basically just rubber suction like cups that provide more surface area for the legs so that they do not end up sinking in the sand.
Disregarding the shoulder leveler altogether
Each tripod comes with a leveler that has some sort of liquid inside it. Make sure that you actually check this before you let your hands leave the tripod with your camera mounted on it. The slightest and the most minor of imbalances might end up with really disastrous results. That is not something that you would like to happen to your gear. It will only take you a minute or so to check if the tripod is perfectly balanced so you might as well take your time and not rush through things. It will save you an awful lot of time and frustration in the long run.
Not removing the camera from the tripod before carrying it on your shoulders.
You will have to move around a lot when you are covering wedding events. This will require you to change the position of the tripod every now and then. You will need to make sure that you actually dismount the camera from the tripod before you fling it up on your shoulders and move it to a different area. A small misjudgment of distance and dept might leave you to crash your camera against the wall or a tree or anything solid if you leave it attached to the tripod the whole time.