Besides numbers, there are many kinds of transition words that you can use.
Time markers can sometimes work well: next, then, subsequently, later.
Other useful markers: for example, on the other hand, despite this fact.
One great source of examples of transition markers is this page from the Purdue University Online Writing Lab (OWL.) Though originally designed for university students, this website is a really valuable resource for all writers who want to learn more about how the writing process works.