There are many trusted sources like Fivver, Upwork that can provide you with online job opportunities in any domain. Not only you will find many job opportunities to work online, but you can also be assured about receiving the payment from the clients too. You can even search for the virtual assistant jobs in normal job portals like Naukri and monster and fulfill your dreams.
You can pick writing jobs directly from a live job board or have to bid on a job and hope that the job is awarded to you by the relevant client, depending on how the site works. Some sites may require you to take an English grammar and writing test and some may require you to submit a sample or samples of your work while others may require you to take a grammar test to evaluate your skills. If you pass any relevant test, the relevant site will let you take on writing jobs.