You need a BIG water-resistant shop vac, a parts manual for your filter, fresh sand, and a place to put the old sand.

How tricky it is, depends on your filter. It's a lot easier on side mount filters, than those with the valve on top of the filter. Regardless, make sure you know what all the parts in the filter are, BEFORE you start. Also be careful about the laterals -- they are pretty fragile, and get worse as time goes on. It would be a good idea to have a couple waiting before you start.

But . . . actually, I thought you'd hire it done.