While brick and mortar shops employ merchandisers to encourage shoppers to buy, successful online shops employ similar practices to encourage shoppers to click and buy. Creative digital companies often employ designers who specialize in the User Experience, because they realize how important it is to capture users and make it easy for them to convert into buyers, even brand ambassadors.
Even if you can't afford to hire out, you can borrow some of their tenants to employ on your own online shop website.
Whether you have one product on a page or if you want to group several on one page (perhaps because they go together or are versions of each other), you want to make sure the page is not cluttered. Like a messy shop, clutter discourages and overwhelms consumers. Bottomline: Make it easy to understand and buy. Use straight forward URLs for inner product pages, and make sure your homepage makes it easy to enter the shop space (a "SHOP" or "PRODUCTS" tab at the top of the page is an easy way to make that happen).
More purchase buttons is not better! Don't scream at your potential buyers, persuade them with taste, personality and above all clarity. Your purchase buttons should be prominent, placed below the description of the product and near to a large, clear image of your product. And only have one purchase button on each page. You'd be hard pressed to find a person who loves a pesky salesperson, and huge purchase buttons all over the place are the online equivalent.
Again, clarity is key. Your font choice should be clean and easy to read no matter where your potential customers are looking at it (test on mobile!). While font choice may seem like an excellent opportunity to show off your personality, messaging and imagery are actually safer bets for that. Designers will help you walk the line between expression and clarity but if you aren't using one, make sure you are never using a kitschy font like (the universally loathed) Comic Sans or even the (slightly less hated) Marker Felt. Instead, steer towards classics like Helvetica, Futura or Univers.