No THIS is a really important subject and can not be avoided regardless of if you are attending vacation, wedding, nature or any other subject. And it really do start with the basics of technology regardless of equipment.
There are tons of stories from any wedding with pictures that became to dark, to light, missing ha head, missed the important kiss and so on. And the reason is always that preparation and choices made messed up the all important moment. So before going to the scene of the event of a lifetime there are a few things to consider.
Start a few days before the big day to charge the battery of your camera since this is no1 reason people leave it at home. When you are all dressed up it will be too late to do any charging of the camera that ensure it will be working the entire time. Some people do forget that low light photography (most common in churches and public areas) do drain the battery in a few ways.
First of all the auto focus may need more attempts to be exact if there are a lack of contrast on the subject. Second when it is darker the shutter usually stays open for longer than in good lighting and this also drain the battery. Flash photography (built in flash) and sometimes the temperature (cold) limits the battery life. With a fully charged battery it will not be a likely problem, however starting out with a half full may take you just half way through the event.
Second empty the memory card, put it back into the camera and spend some time cleaning lenses and select one or two lenses to carry with you. A big telezoom should not be needed for shots like this, you will be better off with a max of 200 mm lens and some planning. If possible stay in the 50-85mm range (35-60mm DX format) and plan to get close up to the events.
Try to get a seat close to the ailse so it will be possible to move around a bit without distracting anyone, there are some key moments to shoot. When the ring is put on the finger, the kiss:-), when the bride and groom have a seat together for the first time and when they exit the building are important. This because most of the spontanious emotions will be projected at those moments and will give more feeling to the image.
Do your best to enter the location of the wedding itself and any locations that the couple will be during the day early, preferably the day before. This gives an oportunity to pick out a few spots to get the personal pictures aside of the crowd. A park bench, stairs, nice car will be good choices. Personally I do belive that threes are out dated as a item in a wedding photo, it is simply to much used by others. Try to get the shots as close and personal as possible, it will create good scenes.
Be ready for the unexpected and if you think on intuition that something different will occur then take a picture! Sometimes the memory for life will be a picture with the bride giving an extra smile to a parent, the groom picking up a child or any other split second event no one else care about. Until they see Your picture!
Depending of your level of skills consider the light meassure setting on your camera and if it is a white location with good lighting you may be good with Matrix (average) light metering. Should the building/room be darker with only a couple of windows then center weighed may be best. Then, if you keep the main subject at the senter of the picture they will turn out nicelly when printed. Windows and light will tend to become to bright but this is not important compared to have the newly wed dark beyond recovery.
The day after taking the pictures upload the images and select the best ones, you may want to present a photo book or a series of pictures. It will require you to adjust the pictures and crop them to get the correct framing, lighting and so on to a finished print.
Always remember that the moment you are experiencing will not come back at any point in life for any one involved and pictures will make a difference. It is really important to remember this and in the best way you are able, make yourself and the main people involved proud of the day. Prepare for it and enjoy it!!