The easiest way is to ask questions. Even neurotypicals get themselves into trouble by making too many assumptions. So try not to. When somebody tells you about something that they seem to like talking about, ask them more about it. Even better, ask them if they'd be okay telling you more about it to make sure you didn't assume incorrectly that they liked that subject. Ask them about things they care about or put effort into, like their clothes if they have a funny t-shirt or a nice looking outfit. Once you know a person better, you can even ask them how they like to be treated and how they like to have conversations.
Just stay curious about everything and avoid making assumptions. That alone will make you better at conversation than a lot of people.