I suppose there are similarities with a wedding.
e.g.
Get there in plenty of time, speak with the minister
Check what you are allowed to do at the church/venue, e.g. flash, position when you can take pics (courtesy usually appreciated!)
Have you found out who the family want included - you may be able to gather groups around the font after the actual service to get the combinations you need (grandparents, siblings, Godparents, etc.)
Good luck and enjoy!