Upwork: This website offers a great marketplace for selling just about any professional service. You don't need a merchant account, website of your own or anything else for that matter. All you need to do is be able to provide a high-quality service at a reasonable price. But be informed, you will have to compete with many others that are constantly bidding on open jobs.
If you're ready to enter the ecommerce fray, you could sell your own stuff. Of course, along with selling your own stuff on your own website comes a whole slew of both responsibilities and technical configuration and requirements. For starters, you'll need a website and a hosting account. You'll also need a merchant account like ones offered by Stripe or PayPal. Then you'll need to design that site, build a sales funnel, create a lead magnet and do some email marketing.
With drop shipping, you’re effectively partnering with a manufacturer or wholesaler to sell their products. This way, you don’t pay upfront costs to buy inventory, aren’t sitting on unsold items taking up expensive warehouse space, and don’t have to deal with shipping the products yourself. You simply create your site, fill it with drop shippable products, and drive in customers, with almost everything else done for you.