I would test the limits and then see if it would be an possible to advance human progression, like giving life to Mars or other planets and making it habitable, or reviving genius inventors and great minds and make them semi immortal for greater progression. I could even enhance the physical and mental prowesses of any newborn children, get rid of diseases, or make plants and animals more plentiful.

I will create a life form that is very superior and can self replicate infinitely and has the capacity to take many forms it wanted but also loyal to me though and uncompromising then give a stich of little bit of humanity the good parts at least. In my analogy for this is kinda how God created Lucifer but this one isn't going to rebel against me I would make it the perfect lifeform wisest and the most beautiful and powerful I would just create other lesser beings just for it to develop. A sense of identity then there you go I had an army and a powerful henchman

I would try to see if i have mastery over my own life

That too