Takes time, but worth it
I read many, many reviews to try and glean some sort of best process to do this for those that had success with these.  I finally got time to get mine on the wall (and they look fantastic, I'm so happy with the end result) and this is what worked for me: flattening the large roll of paper that the stickers come on, cutting out the shapes and hanging up with painters tape before applying, take pictures once you have your preferred pattern (painters tape only holds for so long), have a buddy helping out to keep you sane.  Each person will have their own idea for layout, but if you want clusters like I did (in pic), really think about what needs to go down first because while you can lift and replace on the wall ok, maybe once or twice, the stickers stick REALLY WELL to each other and are not as forgiving.  I put down leaves first and then went flowers, placing down any leaves that I had overlapping as needed.  It worked best for me to start a sticker and keep the back on and kind of roll that paper up as I set the sticker on the wall, especially the bigger flowers.  I also bought tools to help smooth them out and prevent air bubbles as I pressed them down, it helped so much.  One reviewer suggested to heat set with a hairdryer if you plan to have them up for a long time, I did that, seemed to help.  They've been up for about 2 weeks now with no problems, no hint of peeling up or falling off the wall.  This went in my smaller room that I use as a home office/guest bedroom and I used every sticker from the 2 sets that I ordered.  Took me about 6-8 hours total with help (slow and steady).  Very happy with how it turned out.
Rating: 5 stars