Well, obviously it varies... and usually, I think what's most going to determine where you start a new chapter is where you ended the previous one. Broadly speaking, my chapters either end with the close of a scene, or they end on a cliffhanger (occasionally, both at once). Typically, if I'm wrapping up a scene in the previous chapter, I'm going to do some kind of jump cut, moving ahead anywhere from hours to weeks in in-story time. The next chapter then starts out by introducing some new scene, and if necessary some sort of recap of the amount of time that's passed and/or what's happened in the interim shortly thereafter. There are exceptions... I'm pretty sure I once started a chapter with "that had been three years ago," or something to that effect, rather than opening with a new scene per say. I figured stating that an extreme amount of time had passed between this chapter and the last would have more impact than simply starting out with a scene that would either be confusing or which could have happened much closer to the end of the previous chapter. Also dangerous when you're doing a serialized fanfic format where it might have been several weeks since you posted your last chapter ("Wait... what was happening last chapter? What was three years ago?"), but eh, I went with it anyway.
On the other hand, if I ended the previous chapter on a cliffhanger, then I might continue the scene I'd been going off in the last chapter--resolving the cliffhanger. Alternatively, I might put the resolution up in the air for a while and go with the usual "new scene" kind of opening, if I think it would be better to further build suspense to the cliffhanger resolution. It honestly just depends on what I think will play into the readers' interests better.
But to me this seems kind of like a weird question. I mean, you start the next chapter with what happens next in the story (not necessarily what happens next in time)... that's pretty much all there is to it. Or if you're talking about how it's usually hard to just look at a blank page and dive into writing, then I guess my advice is the same--think of what comes next, and just start writing. Don't worry about if what you're putting down is going to be any good or if you're going to have to throw it out later; you can always go back and change/delete the beginning later, and it will be much easier to do so after you've actually got some writing behind you and know more or less how the chapter's going to turn out.