Some things that might help (because they did in Fo3, and NV is the same engine and probably also the same basecode):
1) Set the game .exe to allow more than 2gb of RAM to be used, this will greatly reduce crashes (may not be aplicable to NV).
2) Make liberal use of the "pcb" (Purge Cell Buffer) console command durring play, apparently the game does not auto-crop all the Cell's it's storring in RAM, so you'll have to do it for it (reduces crashes and improves performance when it's gotten bad after a while).
3) Disable all Auto-Saving, and never use Quick-save either, press ESC and do all your saving the old fashioned way, and allways save to a new file (and do it often! you never know when it'll crash anyway).
4) Sleep, lots, go on 4 day (4x 24h) or even longer sleeping binges on a regular basis, this will reset the gameworld, and any glitching out ragdolls and other nastyness along with it that may cause the game to run unstable, it does wonders for crash-prevention (remember how i said my last Fo3 save was totally borked? sleeping for a week fixed it!).
5) If you like using mods (and you probably do), learn how to make a "merged patch" with apps like Fo3Edit, it'll vastly reduce the chances of conflicts (but broken mods allways will be broken, and should be disabled if found).
6) Save before every Quest no matter how big or small, for every one of them, there's about 20 ways you could potentially break the scripts, just by doing something the Dev's did not anticipate.
7) Never use the Pib-Boy Radio, it is a thing of evil and crashing.
Do the above, and you will only have the odd random crash every once and a while, fail to do the above, and the game may well become unplayable over time (sure it'll start off fine, but all thouse glitches eventually catch up to it, and then it's crash city!).