When I have the space to do so, top hinge and cut between the letters. When I first started, not that long ago, I would cut into very small sections when possible. That way I could apply each section with one downward squeegee stroke. This method worked great but is sllooowww as heck.
As I became more experienced I lengthen the sections more and more. Now I like to do sections that are, oh, say 12-18” or so wide. I find by curling back the liner but leaving it attached I can keep the vinyl taut and apply with virtually perfect results.
I just completed a job with half dozen 4x8 signs with full length lettering by myself. Not a bubble or wrinkle to be found. I give a lot of credit to the Rob Ivers instructional tapes (and this forum, of course) as I have no formal sign shop training.
Now when I have the luxury of having a helper nearby I'll use the end hinge method. Last week we did a semi with some long 12"x60" graphics. After we lined it up and used some pieces of tape at the far end for alignment reference my helper kept the graphic just barely off the surface and one swipe with the Big Squeegee had it applied, literally, within 10 seconds, bubble and crease free.
If I’m doing a long solid graphic by myself I’ll typically use a center hinge. Probably not the right way, and you must be very careful to avoid a telltale ghost line where the hinge was, but I find it works well for me. And, again, the Big Squeegee really raised my confidence level on these installs. Enough so that I just ordered 2 more yesterday.