The thing that's always helped me is to do a good deed in the deceased's name. Instead of buying flowers, make a donation to any charity or worthy cause that your cousin might have cared about. It doesn't matter if it's only $5, because it's the principle that's important. In that way, your cousin's final act on earth will be an act of charity.
I have lost my whole family, I am one of 7 kids and they are all gone. First off, I am very sorry for your loss. It's such a suffication that one or I feel about loosing the people I love. personally, I have to ask, Why do you have to say goodbye. I did'nt. I told them I will see them at some point, but it isnt my time yet. I asked them to watch over me and my kids. Then I just talked to them like I always did. Told them I loved them. You will know what to say when you get there to do it. I hope he/she was'nt young? Good luck and again, I am soooo sorry. My prayers will be with you on your difficult day.