If your funeral venue is a crematorium, it is good to claim this institutional space and make it yours for the time you are there.
You make the space yours by playing your own music in it. You can also do it by displaying photos or, better still, one big photo of the person who has died, and placing it beside the coffin. A closed coffin depersonalises the person inside it; a photo alongside reassures everyone that the owner is in residence.
Lots of photos on and around the coffin work well.
So do mementoes. You can personalise the coffin with a favourite garment of the person who has died. A hat works well. So does a rug or a throw. You could lay a favourite coat over it.
You can display around the coffin emblems of the person who has died. Golf clubs. Motorcycle boots. A gardening tool. Pots of jam.
If the service is at the crematorium you need to get it all in and out smartly.
You can decorate the venue more extensively, of course, with drapes, banners or whatever. You will need time to set up, and then time to take it all down and out. If your venue is the crematorium, your best bet will be to book a double slot.