I used this balloon as a photo prop for my three-year-olds birthday and I wanted to add some tassels. Now, if you plan to use tassels for a garland, I would recommend making a tassel more like this. For that tutorial, the top of the tassel looks more finished. When adding it to a balloon, you don't really see the top of it and you want to make sure that it is stapled to the balloon string. So this is the easiest way to make a tassel specifically for a balloon.
Open the sheet of tissue paper and cut it down the center
Cut little fringes in the tissue paper
Roll the top portion of the tissue paper that doesn't have the cuts
Twist the top of the tassel
Open the tassel just a few inches and wrap it around the balloon string
Staple the top of the tassel to the balloon string
Continue that method with the other tassels, making sure to staple the next one high enough so that the one above it covers the staple.
To purchase the balloon, I thought I would be awesomely proactive and just buy them on Amazon way ahead of time. Then I brought them to Party City to get one of them blown up and I realized I didn't buy "helium approved" balloons-definately and oversight on my part. So now my kids have some giant balloons they can blow up. So I had to buy a whole package of these giant balloons from Party City and then pay to have it blown up. But now I think I will use a balloon for my boys birthday's too because I have some extras :) I know you can buy these balloons online, just make sure that they are able to be filled with helium :)