I like using x and / to expand certain phrases. For example, ivp=IVP, ivpx=intravenous pyelogram, and ivp/=INTRAVENOUS PYELOGRAM:
I try to apply the same rule generally to make it easier for me to remember my shortcuts, so cns=CNS, cnsx=central nervous system and, were I to use it in a heading, I would use the slash to expand cns/ to CENTRAL NERVOUS SYSTEM: It's helpful to me to use and expand acronyms this way, so I have turp=TURP, turpx=transurethral resection of prostate, and turp/=TRANSURETHRAL RESECTION OF PROSTATE. This way I can use pretty much the same shortcut for the phrase whether it be expanded or not, and regardless of where it is dictated. It also helps me to use commonly used acronyms to remember these.
This doesn't apply to words and phrases that come up often and don't need to be set apart like that. I like to use 'tol' to expand The patient tolerated the procedure well, and I leave it without punctuation in case I need to add to the end. I otherwise use shortcuts for words such as 'otherwise' (ow), without (wo), throughout (tho), available (av), increased (inc), decreased (dec), fracture (fx), diagnosis (dx), etc., and phrases like within normal limits (wnl), normal in size (nis), the patient (tp), the patient's (tps), etc.
I'm using n in certain cases too, i.e., ex-exam and exn=examination (as above), and cath=catheter and cathn=catheterization, etc. In this (and other) cases where the word might appear lower case in the body of the report but capped in a heading, I use cath/ for CATHETERIZATION, exn/ for EXAMINATION, etc., where cathd=catheterized and exd=examined.
Other mnemonics include wow=without and with, csac=cul-de-sac, sped=special education, etc.
I might save a few keystrokes if I shorten some of my shortcuts, but then I wouldn't find them as easy to remember. I've gotten so used to these my fingers just go there automatically--a good thing!
I like the double consonant idea. I'm going with rr=right and ll=left and thinking about other ways I can use this too.