Well I am by no means a crappie killer......... But This works with most any species, get a good lake map and study it......patronize your local bait shop and ask general questions.........If you support their business they should tell you basic info like they are bunched up in cover in 15-18 ft of water or they are out in front of secondary points.......Etc.
Then you can study the map and figure likely area's...........Talking to other folks at the landing may get you some intel........ it just takes time and leg work on your part.
Fisherman are historically tight lipped ( pun intended)........but as the same fisherman see you more and more at the launch they may well help a little more.
Also I almost forgot........ search the net for fishing reports, look on you tube for video's of fishing on your lake.........the more info you gather the more you are able to build a working plan........
Three can keep a secret................If two of them are dead! (Benjamin Franklin)