Decide what you are actually selling
Before any software decision, write one sentence describing what you sell and who buys it. A store that sells "handmade ceramic mugs to people furnishing a first home" makes every later decision easier: the photography, the price, the shipping box, the words on the homepage.
If you cannot write that sentence yet, start with the products you can reliably get hold of, at a price that leaves a margin after packaging, postage and payment fees.
Work out your numbers before you build
For each product, note the cost to make or buy, packaging, postage, and roughly 2-3% plus a fixed fee for payment processing. Subtract all of that from the price you intend to charge. If the number left is uncomfortable, change the price or the product now rather than after launch.
Set up the store
A first store needs surprisingly little: a name, a web address, a handful of products with honest descriptions, a way to take payment, and a shipping rate that does not lose you money. On Community E-commerce you answer five questions and the storefront is built for you, so this stage takes minutes rather than weekends.
Photograph your products properly
Product photography is the single highest-return task for most new stores. Daylight, a plain background and a phone camera beat an expensive setup used badly. Shoot each product from the front, at an angle, in use, and close enough to see the material.
Write descriptions people can act on
Say what it is, what it is made from, what size it is, and who it suits. Answer the questions you would ask if you could not touch the item. This is also the content search engines read, so plain, specific language does double duty.
Turn on payments
You will need business details and a bank account. Test a real transaction before launch, refund it, and confirm the money and the refund both appear where you expect.
Decide shipping honestly
Flat rate is simplest and works when your products are similar in size and weight. Weight bands are fairer when they are not. Free shipping is a marketing decision, not a free one: build the cost into the price or set a minimum order.
Launch to people who already know you
Your first orders almost always come from your existing network. Tell them directly, individually, with a link. Do not wait for search traffic that takes months to build.
Then make it findable
Give every page a clear title and description, keep your URLs readable, and publish content that answers the questions your buyers ask. Search visibility compounds slowly and then all at once.
What to do in your first month
Ship every order quickly, ask each buyer how it arrived, fix whatever they mention, and add one new product or one new piece of content each week. That rhythm beats any launch-day tactic.