Beginner MTT/STT question - The Middle game

[sfgiants]

I don't have much experience in tournaments, but I do fine in the beginning by playing super-tight and I do okay in the end by pushing to pick up blinds when I have fold equity. However, there is a point right in the middle where I don't know whether I should continue playing tight and just let my stack dwindle down until my M hits 10 or so and then begin pushing or of I should I open up my range more and play more "poker?" What would be the standard approach?

Also, does this strategy change with STTs? I'm guessing in MTT's you have more room to play poker whereas in STT's you just let your stack erode and then push at M=10 or so.

Any thoughts appreciated!