In the arrangement in the link above, they've used pittisporum clustered at the bottom of the vase. Not only does that give some visual "weight" that gives balance so the whole does not look top heavy, but it provides a mechanism to hold the stems upright. Any leathery foliage plant you have growing will work.
Here's a link with some good tips about harvesting and processing cut glads:
I like this one. This would be easy for a novice, as the stems are all just clustered upright. You can use any kind of greenery at the bottom, and stones, marbles, fruit, shells, or Christmas balls could be used to fill the bowl.
Every year at our Mineapolis Home and Garden Show, there are about 40 or so very creative arangements made by local designers. Most do not even use conventional vases. There is a judging, but little if any financial reward. This year, the show administration declined to pay for the materials, and every designer opted not to display. A very unfortunate matter.