One strategy of finding a plausible way to a specific chord or to a key change is to work backwards from the target chord. This works particularly well if the music that you’re writing is mainly cadential harmony as you can simply look at your target chord (let’s say C) and find a way to it by adding a dominant chord before that (G(7)), if you now look at that dominant chord, you could either place a IV(F) chord in front of that or a ii(Dm) and so on. There are of course several paths that you could use. The advantage of working backwards is that it is easier to find strong chord relations. As mentioned before, this works very good with classical cadential harmony but also works in a more filmic context by using “filmic cadences” (such as bVI bVII I etc.) while the strategy of working backwards remains the same.