Fill the bottle up as much as you can with a hummingbird feed. Here is a recipe that I found via Thrifty Fun,Bring 4 cups water to a boil and stir in...
Step 4: Double checking
Take the piece of tubing you just cut, and push it through the hole on the cap that you just drilled. You want it to be fairly snug, and if it is too loose, then find a new cap and drill a slightly smaller hole.
If the piece of tubing is secure, then we can move on.