Some basic things you may wish to consider,

Use a Professional,

Your day can not be re-shot, emotion can not be recreated, accidents can always happen, but they are less likely to do so when you use a professional.

The weather,

If you are considering an outdoor location for your photographs it is best to have an indoor back-up location in mind, as the hottest topic around is usually how bad the weather is or the weather’s not what was expected.

Time

Leave enough time in your plans for the day for the photography, this should be an estimated 3  hours

Time of year

As above it can take 3  hours for your photography, and while a 1pm or 2pm wedding in the summer months is pleasurable, in the winter months it leaves no time for outdoor photography as it can be dark as early as 3pm in December.

Pressure

It is your day, do not allow anyone else to pressurise you into making decisions you are unsure of.