There’s nothing wrong with writing lists – they work well online where attention spans are shorter.
If the list items are short, you can use bullet points. Or, if the order is important, choose numbered bullets.
Both make text easy to scan and read quickly.
Another, more elegant, approach is to write a variation on this:
First, something happened. Second, something else. Next, we used an elegant variation to make things more interesting. Then, we did this. Last, we finished up.
Spell out the words from first to ninth* then write 10th, 15th, hundredth.
Some people use firstly, secondly, thirdly and so on. While strictly speaking both approaches are grammatically correct, I’d argue adding -ly is old-fashioned and unnecessarily fussy.
What’s more, you’ll end up looking silly if you want to deal with lots of items and reach eleventhly or even millionthly.
So, stick with the simpler format.
* or perhaps tenth. This depends on your taste or house style, but remember to stay consistent.