Flow of jobs depends on your area and your competition. Some areas have more than enough jobs to go around, some have relatively few jobs, some areas have virtually no shoppers and some areas they are crawling out of the cracks in the job boards.
As a beginning shopper it makes sense to take one job from each company that you register with who has work in your area. Get a sense of the company, their instructions, their pay cycle and their responsiveness in general. Based on a first job, decide whether to repeat that job in other locations and/or to try other jobs they have to offer. You are at the stage where you are starting to build your reputation so strive to make every job perfect. You will find that jobs you have performed before become easier and if it worked well you are in a position to take a nice handful of them when they post in the future. Within a few months you will have identified which companies work well for you.