As for X: X + thì …

Thì after a word or phrase at the start makes it the topic, like "as for …": Cà phê thì em uống, trà thì không. Coffee I drink, tea I don't. What comes after thì is what you say about it.

The topic is very often set against something else: Món này thì ngon, món kia thì không. This dish is good, that one isn't. You know còn … thì for switching to someone else; here thì does the job without còn.

The topic can be a person, a thing or an action: Đi thì được, nhưng phải về sớm nha. You can go, but come back early. Said twice, it's a shrug: Đi thì đi! Fine, let's go.

With a plain describing word and nothing to contrast, thì is usually left out: Món này ngon. Adding it hints that there's more to say: Món này thì ngon, mà hơi mắc. It's good, but a bit pricey. A topic can also be followed by a whole small sentence about it, with no thì: Cô ấy tóc dài, she has long hair.

You've also met thì after nếu, where it marks the start of the result. At the start of a reply, Thì … is like "well, …": Thì em cũng muốn đi, mà bận quá.