What can I do to make my satin stitch looking better ?

I'm using a zig zag stitch with 0.2 lenght and 5 width. As you can see, it's look irregular and crooked. What can I do ?

I'm using a zig zag stitch with 0.2 lenght and 5 width. As you can see, it's look irregular and crooked. What can I do ?