These are simple 2 key expansions for some very commonly used LaTeX elements:

`^   Expands To   \Hat{<++>}<++>
`_   expands to   \bar{<++>}<++>
`6   expands to   \partial
`8   expands to   \infty
`/   expands to   \frac{<++>}{<++>}<++>
`%   expands to   \frac{<++>}{<++>}<++>
`@   expands to   \circ
`0   expands to   ^\circ
`=   expands to   \equiv
`\   expands to   \setminus
`.   expands to   \cdot
`*   expands to   \times
`&   expands to   \wedge
`-   expands to   \bigcap
`+   expands to   \bigcup
`(   expands to   \subset
`)   expands to   \supset
`<   expands to   \le
`>   expands to   \ge
`,   expands to   \nonumber
`~   expands to   \tilde{<++>}<++>
`;   expands to   \dot{<++>}<++>
`:   expands to   \ddot{<++>}<++>
`2   expands to   \sqrt{<++>}<++>
`|   expands to   \Big|
`I   expands to   \int_{<++>}^{<++>}<++>

(again, notice the convenient place-holders)

In addition the visual mode macros are provided:

`(  encloses selection in \left( and \right)
`[  encloses selection in \left[ and \right]
`{  encloses selection in \left\{ and \right\}
`$  encloses selection in $$ or \[ \] depending on characterwise or
                                      linewise selection