de-tune the string first.    If you're raising the saddle, its also going to be 'raising' your string and your tuning will change.   Usually not a big deal, but if the strings are older and you're raising the saddle a LOT, then it'd be easy to break the string with your face up in it.   Don't ask how I know.

Lots of other things to consider.   If its too low even at the nut - you might need a new nut cut with slots that aren't as deep.     But if its fine there, just too low towards the "back side" you should be fine to just raise the saddle.   There's two little screw thingers that will both take a small "allen wrench."   Clockwise to extend the little posts and raise the saddle.    It shouldn't effect your strings intonation enough to matter, so this is something you should be able to do yourself.