Just to expand on what Bryan has eluded to with Stellarium, I use Stellarium to tell me what constellations are where and when. Stellarium has a fast forward and a rewind button so you can move ahead in time and plan your time under the stars, either for that night or a particular night further down the track.
I then get my "Atlas of the Southern Night Sky" (a handy investment for around the $50 mark) out and go to the various constellations in the book and it will tell what DSOs are in each particular constellation, their visual magnitude and size. Each constellation comes with it's own sky map so you can gain a feel for how to find things (star hop). Personally, I'm too lazy for that
, I use GoTo.