here are some strats in texnique ; . arranged approximately in order of well known ness

omitting spaces (this is kind of trivial) and they can be omitted before numbers for example like u can do \pi2 instead of \pi 2 (dumb example)

omitting {} for 1 character things . this is really useful especially with things like \binom and \frac for example, instead of doing \frac{1}{2} you can just do \frac12. really helpful in continued fraction for pi/2 and alternating harmonic series. also helpful in a bunch of others.

things like \lang instead of \langle or \le instead of \leq

\bold instead of \mathbf or \textbf . really useful in things like stokes and spectral and cauchy swarz . (similar for \text instead of \mathrm but this is inconsistent) (inconsistent orz)

\frak instead of \mathfrak (this is only used in continuum)

\R \Z \N instead of \mathbb R \mathbb Z \mathbb N . saves a lot of time and can be found in a few formulas like fundamental group of circle or continum


this last one is kind of sus . but :
u can use \rm instead of \mathrm but only at the end of a section . so like u cant use it on \mathrm dx etc but u can use it on like R_{\rm sw} instead of R_{\mathrm{sw}} in moist which is useful . similar things can also be in other formulas with very little # of time saved (for example in stokes u can do \bf\Gamma instead of \bold\Gamma but only on the last gamma
this will let you get moist 20% faster