A good start...
but I'm not sure it's actually a decent finished product. You had a lot more space for buildings in that bottom right bar, but you only have standard turrets, power plants, and a factory?
My best piece of advice would be to have a variety of turrets, and to try to keep them from simply being more powerful versions of each other. Having turrets that each have their own strengths and weaknesses adds a lot to a defense game.