A connected home project works best when it solves a recognisable inconvenience. Starting with one routine makes it easier to understand the setup, notice failures and decide whether the extra technology is worthwhile.
Describe the routine in plain language. Perhaps a lamp should turn on at a convenient time, or a reminder should appear before you leave home. Identify the trigger, the expected action and the conditions in which it should not happen.
Check the official documentation for every component before connecting them. Similar-looking features may depend on different systems or accounts. Keep a manual way to perform the ordinary task so that a failed connection does not leave you stuck.
Try the routine during normal household activity. Ask whether it behaves predictably and whether everyone affected understands how to pause or override it. A clever automation can still be inconvenient if it surprises the people living with it.
Expand only after the first routine has proved useful. A small, understandable arrangement is easier to maintain than a collection of unrelated devices purchased before you know what you want them to do.