Just a few tips that made it easier for me:
1. I used a rotary cutter on the felt, which saved tons of time because I could cut 2 pieces of felt at a time
2. Straight pins do seem to be the best to attach the felt to the foam wreath. I would recommend using pins with red, white and blue heads because they do sometimes show through. It took at least 250 pins for mine, so be prepared!
3. I used 2 vertical rows of three "flowers" each for the red and white sections. This seems to space out the colors nicely
Happy 4th of July!!