1) Flex your knees and ankles. I was a backseat skier forever, it's still something I have to focus on, but somehow being told to pressure the fronts of my boots never got through to me. When you're used to skiing in the back seat, you're generally flexing at the hips, so when you attempt to pressure the fronts of your boots and continue to flex at the waist, you find that your weight is actually too far forward. When I instead think about flexing my knees and ankles and keeping my shoulders more upright rather than bending forward at the hips, my weight stays centered over my skis.
2) Make round turns. I used to ski a zipper line even where there weren't moguls. My tips would stay almost stationary as the rest of my skis rotated side to side around them ("windshield wiper turns"). Focus on drawing that big letter "S" down the mountain. Even skiing a zipper line should involve rounded turns rather than windshield wipers (I was doing that part wrong too), or freeride competitions encourage making big GS turns through mogul fields.
3) Keep your shins parallel to each other. Standing up strong on your outside ski is important, but it doesn't mean your inside leg gets to take a vacation. Drive that inside knee into the turn so the outside edge of your inside ski is actively engaged. Sliding that inside foot back (by flexing your knee and ankle) to keep it almost even with your outside foot will also help you accomplish this.
5) Ski what you want to ski. This is the piece of advice I've found myself repeating the most to freeride competitors, but I think it's also an idea to live by. I spent years trying to ski a textbook freeride line, the problem is that there is no textbook. When I finally quit trying to guess what line the judges would give the highest score to, and started skiing lines that played to my style of skiing, I started having success. Several times I chose lines that I thought would cost me my spot on the podium, but chose to ski them anyway because they looked fun and challenging. It didn't always work out, but most often I was rewarded for creativity and for finding something that I was able to ski well rather than a line that would have been impressive but difficult for me to grease.