Beginner - How can I Develop the Unity Tutorial game 'Roll a Ball' further

Hi

Recently I followed the 'Roll a Ball' tutorial on Unity which I really understood and enjoyed doing. Before I move onto the next project I would like to further my understanding of what and how things can be done. I would like to have a go with re-spawning the pickup objects, adding sound for when pickups are collected, perhaps scripting different drag properties on different terrains and I would like to have a go at making the game look at a bit more attractive.

As I understand everything in this project already, It made sense to me to try and keep on developing it to help me understand more. If anyone can help me out with any of this I would be very grateful. :)