Here is an example to illustrate how quickly you can wrack up points, as well as easy ways to reduce your impact.
Walking to class or work one morning, you decide to stop for a hot mocha latte at Starbucks. It is absolutely delicious, of course. Unfortunately, you have just gained at least three points for No Impact -- the lid, the cup, and the sleeve. Possibly two more if you used a pack of sugar and a coffee stirrer. If you got a pastry to go, you also have a paper bag and the napkin they used to pick it up with. Did you get a receipt? That counts, too. Now you're up to 8 points for one breakfast.
So what do you do? How do you make sure that you don't get as many points in one breakfast as some people get over the whole two weeks? Maybe the next day you take your travel mug with you to Starbucks and have your mocha latte from that instead. You're down to five points. Perhaps you also bring a slice of toast or bagel from home, and now you're down to three. You can skip the sugar (or bring some from home) and use your own spoon to stir it -- you're down to one single-use item: the receipt. And at some places, you can ask them not to print your receipt, and you're down to zero. Does this seem over the top, carrying sugar and a spoon around with you incase you get coffee? Maybe. But that's how you win the No Impact Challenge, and after a while, it becomes habit.
How does this relate to policy change? That's up to you. Maybe this gives you the idea to write a policy that gives subsidies to cafes who reward their customers for bringing their own mugs. Or perhaps after grocery shopping and realizing the number of plastic bags you use, you write a policy about instating a local bag-ban (which is how No Impact got started in the first place!).