Definitely be sure to have a list of photos you want taken. For example, who do you want in the pictures? Family, combined Families, Wedding Party, Bride/Groom only, Flower girls.
I wouldn't go to crazy with providing tips to the wedding photographer this is what they do for a living. The only tips I would provide to him is if there is a certain shot that you are interested in, or ones you don't want. Also if there are family members you really want to be photographed.
1. If mother or dad of the bride is paying, make sure you know what pictures they want
2. Most brides prefer candids rather than staged portraits-concentrate on those.
3. Always get good family portraits ithe the bride and groom
4. Offer some black and white photography-gives a better and deeper perspective.
I would suggest taking more than one of a picture if you are able to. This will make sure you don't have a blurry one of something very important to the customer.
Give the photographer a list of important people (grandparents, godparents, etc) and where they will be sitting. Also, let him know what staged shots you want and where.
Keep taking pictures at all time. Do not get in the way of the ceremony. People are trying to watch. Do not stand in the way of the Bride and groom when they are entering into the catering hall.
One of the best tip I can give a wedding photographer is to make sure you have enough flash. Flash is very important for indoor picture taking. Another good tip would be to encourage the bride to choose a variation of color and opt for some black and whites.
