Watering
Watering comes up sooner than most beginners expect. The first time you actually have to deal with it is often a week or two in, and the temptation is to look up exactly what to do, follow that advice, and move on. The trouble is that watering responds to the specifics of your situation more than most other parts of indoor plants, and generic advice tends to almost work and then slowly stop working.
A more durable approach: understand what watering is for, not just what to do about it. Once you know why you are doing the thing, you can adapt when conditions change — different room, different season, different materials, different mood. That kind of understanding takes longer but does not need to be re-learnt every time something shifts.
That is the short version. Indoor Plants rewards patience more than cleverness, and almost all of the visible improvement in the first year comes from showing up regularly rather than from any single decision about gear, method, or soil and pots. Most of what is on this site assumes the same thing: that you intend to keep at it, and that you would rather be quietly competent in two years than dramatically excited for two months.