I'll bet you didn't ride a bicycle perfectly the first time you tried that, either. :)
There's a lot to learn to coordinate all at one time! Stick with it! Practice!
Draw your designs over and over and over - use paper and pen or a dry erase board. Draw a design until you can almost do it with your eyes closed. Draw it until it's automatic and you can do it without even thinking about where to go next.
Do your FMQ on a practice sandwich. Just do straight lines, first. Then go to wavy lines, then lines which reverse direction. Start simple and when it's simple for you, go to the next step and stay there until it's simple for you, too. Have fun with it! :)