Upload & Sell: Off
The fact that they've asked for photography is helpful to you. It means you have room to ask for permission, namely, to be there early with the family as they prepare. This is as useful in funeral photography as it is in weddings; perhaps more useful, as some folks don't anticipate having a someone operating a camera on the day of a funeral. Being there with the family, early, gives you time to assure them you'll be respectful, discreet, and supportive. Shoot getting ready like you shoot wedding-day getting-ready shots, but with even less interaction. But be there, with them.
Plan to find vantage points and wait, rather than moving around a lot -- both at home before the service, and of course at the service. This seems obvious, but it bears saying.
Think in black and white. The day will feel black and white to the family, and probably to you, too. So think in those terms and shoot for lots of black and white images.
Ask for access to photographs of your cousin. Try to do this work for the family -- ask for access, not for them to collect and deliver a bunch of images. It's very, very hard for the family to do anything with images of the deceased other than remember, and cry. So just ask them where the photos are and for permission to retrieve them, unless someone has already compiled a collection. Include some of these photos in your finished product, if you're doing a slideshow or something like that.
Have a 70-200 or similarly long lens handy.