Please remember the following:
Your phone ringing would be highly inappropriate and would cause a disturbance. Turn off any ringers or notifications. Even better, leave your phone at home or in your car. A funeral is not the time to be texting or checking your messages.
From a very young age, children are aware of death, and if the funeral is for someone that was close to them (grandparent, aunt, uncle), they should be given the option of attending. If it is not appropriate for your child to be there, or if you feel they will cause a commotion, it might be best to find appropriate care for them for the day.
Funerals are obviously a time of grieving and mourning, but remembering the good times helps with the healing process. Sharing a funny and appropriate story is acceptable, and in some cases, it's exactly what the deceased would have wanted.
If food or drink is served, don't over-do it. Remember that you won't be the only attendee. If alcohol is served, limit yourself to one or two.