Most of the conferences in Computer Science publish proceedings with Springer, IEEE or ACM (even though there are several dozens which self-publish or publish elsewhere). All three publishers have lists of upcoming conferences:
Springer
LNCS: http://www.springer.com/computer/lncs?SGWID=0-164-12-73665-0
CCIS: http://www.springer.com/series/7899
LNBIP: http://www.springer.com/series/7911
LNCS: http://www.springer.com/computer/lncs?SGWID=0-164-12-73665-0
CCIS: http://www.springer.com/series/7899
LNBIP: http://www.springer.com/series/7911
IEEE
http://www.ieee.org/conferences_events/index.html
ACM
http://www.acm.org/calendar-of-events
Other great resources are mailing lists:
Mailing lists
DBWorld https://research.cs.wisc.edu/dbworld/ AISWorld http://www.aisnet.org/AIS_Lists/publiclists.aspx ACM SIG-IR list http://www.sigir.org/sigirlist/ ECOOP info list http://web.satd.uma.es/mailman/listinfo/ecoop-info
DBWorld https://research.cs.wisc.edu/dbworld/
AISWorld http://www.aisnet.org/AIS_Lists/publiclists.aspx
ACM SIG-IR list http://www.sigir.org/sigirlist/
ECOOP info list http://web.satd.uma.es/mailman/listinfo/ecoop-info
Beware of conferences which do this just for money and not for disseminating knowledge: http://scholarlyoa.com/publishers/ This
This being said - of course the best way is to ask colleagues working on a topic related to yours - like your supervisors, post-docs from your group etc.