Usually, a threaded coupling the way you propose is the only way to connect two different types of pipe.  Sometimes there is a specific fitting made for specific applications (e.g. some pre-made push-on to plastic or pex), but they all serve the same purpose.  A common third party that supports connection to both sides.

Make absolutely sure the threads are the same type on both sides and you will be good to go.  Male NPT goes to Female NPT, Male NPS goes to Female NPS, and the same goes for hose thread, flare, etc.  Do not mix thread types even though they look similar -- a 3/4" MNPT might fit inside a 3/4" FHT but they will never seal properly.

I do use a wrap or two of Teflon tape as well - it helps fill the little gaps that can arise when you have threads of two different material hardness mating.