I took a look at your portfolio and see you only have four images online. The subject matter is fairly common so it will be difficult to find success with what is currently online in your account. My recommendation is to get out and start shooting. Diversify your portfolio, establish a routine of consistent uploads. Take time with your keywords and have fun! As the post above mentioned, it takes time and effort to find success shooting stock. If you are willing to put in the work, the potential for earnings is limitless.
I created a series of videos a while back showing my approach to shooting stock. You may find it helpful. Links to the videos can be found in this blog post: From Shoot to Sale: Part 1 | Adobe Blog
Good luck!
Mat Hayward