One thing that I have watched a lot of writers do is "give up" before they should. Whether it is making money on the internet writing, or finishing your novel--writers need to develop patience. Without patience, you will never be a successful writer.
Now, there are some that will point to my previous entry and say that I am not showing a lot of patience there. But starting over is not giving up. It requires a certain amount of patience to be able to roll up your sleeves and go, "Ok, I need to start back at the beginning, and re-do a bunch of the work I have already done."
When my mom was being taught sewing, her teacher would make her rip out stitches and re-do them if they were not up to par. The same has to be done with your writing occasionally. This requires patience.
Revising a novel after you wrote it requires patience. Very few writers are so good that their first draft is as good as it is going to get. The real writing takes place during revision--do you have patience to rewrite the same story a couple dozen times if necessary? If not, consider another career.
The same goes towards making money as a writer, whether in print or online. When you are engaged in submitting stuff to the print markets, it can be months before you learn the fate of a piece. And novels can bounce from publisher to publisher until they find a buyer. If you don't have patience, you are liable to give up before you cross the finish line.
Patience is also necessary if you are going to make money with online writing. You will make a small faction of a penny per person who reads your material. Not only do you have to have patience to wait for the pennies to pile up, you have to have the patience to advertise your material, and to write more when you are not making a decent profit.
Let's be honest, being a writer is a long lesson in patience. So hang in there, we are in this together.