I wanted to make a piece for the 4th of July, and I really wanted to incorporate fireworks. But I didn't feel like compositing a bunch of photos together of real fireworks and messing around with lighting and everything as I'm going to be hanging out with family and friends at a cookout for the whole day. In thinking to myself, what the easiest way to convey fireworks was simple lines was the answer I came to. What really helped with this, was using the width tool in Illustrator to have these long lines vary in slight widths and then adding dots to the end for the sparks of the fireworks. 
The American flag was pretty basic, after looking up the right dimensions and scaling it down to my needs, to make some rectangles and then space out some stars and add the flag warp effect to it. This was the simple easy way to convey the fun and celebration of the 4th of July.