Recently, an adult student of mine approached me about how she could improve her dancing, telling me she wanted to get to the next level, which for her is pointe work. I am always happy to hear this question, whether it's from an adult or a teen student because that shows me she or he is committed mentally. Often mental focus and energy is half the battle.
The number one thing to improve your technique is consistency. Attend classes regularly - at least twice a week - and you will see your strength and stamina develop. Try as hard as you can not to take off a week or more; this is hard especially for adult dancers because of all their obligations but dance is an obligation too, not necessarily a luxury.
Number two, challenge yourself technically. Step out of your comfort zone in class. Once you can do a double pirouette, push for three - and you'll see your doubles improve! Add beats in allegro, which you can practice first at the barre. If a combination is easy for you, ask the teacher if you can reverse it and practice that on the side.
Number three, go for performance quality. Dancing is not just about technical achievement; it's beauty and art and creative expression. Sometimes the most technically skilled dancers are bland on stage while those who lack certain precision may have outstanding expression in their faces and bodies and we can't take our eyes off them. That's your goal.