Character development in terms of humility would benefit Sasuke in being worthy of Sakura. He has always had a bit of an ego, especially when it comes to his power and abilities. If he can be more humble and admit when he's wrong or when he needs help, especially from Sakura, it would show her that he respects her intelligence and skills. Additionally, he could develop his sense of family. Sakura is all about building a family and a future. If Sasuke can embrace that idea and start planning a future with her, like having children or just growing old together in the village, it would prove his worthiness.
One important aspect of character development for Sasuke would be learning to communicate better. He's always been a bit of a lone wolf, but with Sakura, he needs to break that habit. If he can communicate his love and respect for her clearly, it would be a big step. For instance, just telling her how much he appreciates her presence in his life. Another thing is to develop more empathy. Sasuke has been through a lot, but so has Sakura. Understanding her pain and joys would make him more worthy of her.
Sasuke should work on his loyalty. In the past, he has been a bit fickle in terms of his allegiances. By being completely loyal to Sakura, he can show her that she is his top priority. This means not putting his own revenge quests or other goals above her. Also, he needs to develop a sense of home. Sakura is very much tied to the village, and if Sasuke can see the village as his true home too, and be there for Sakura in that context, it would make him worthy. He could start by helping with village reconstruction or defense, showing that he is committed to the place Sakura loves.