I think it depends on how I'm viewing the file. If I'm just editing in SM and building the tex as usual, then I don't need anything extra. If I'm trying to convert to all sorts of other documents (which I haven't ever really done) then labels, theorem environments, one-line macros, and bib entries cover almost every tex-specific thing I use.
Here is an excerpt from a typical paper's macro section [1]. As you can see they're mostly one-liners to remove the need to keep typing textup and mathbb, simple mathoperator definitions and such.
[1]: http://pastebin.com/RL1gejEZ