I have learned a great deal from a lot of the Dreamstime folks that are willing to share information.
One thing I really struggled with was how to isolate a subject.
If you read the blogs you will find many ways to do this and I have tried most of them.
I really believe that every body will find what best works for them. I find using the sponge tool works the best for me.
But a tip I do have that seemed to turn the corner for me was to drastically crank up the magnification. I mean to over one thousand percent.
At this level your brush size is small even though to you it looks big. What this does is prevents bleeding the white into your subject.
After you make a complete circle around your subject you can start to decrease magnification and increase brush size until it's all finished.
As I said, everyone will find the best method that works for them but this works for me and I hope it helps others struggling like I was.