Below are links to some websites which observers find useful.
Planning Tools:
A Catalog and Atlas of Cataclysmic Variables
https://archive.stsci.edu/prepds/cvcat/index.html
International Supernovae Network
https://www.supernovae.net/isn.htm
Variable Stars Observer - software to help you to plan and log variable stars observations
https://ap-i.net/skychart//en/start
Obsvar - planning tool which uses AAVSO or AFOEV prediction data and other criteria you specify
http://www.astrosurf.com/lcorp/previsionseng.htm
Other resources:
Guide 9 - a full-featured star charting and desktop planetarium program
https://www.projectpluto.com
Project CLEA - educational software used for illustrating modern astronomical techniques
http://www3.gettysburg.edu/~marschal/clea/CLEAhome.html
SkyTools - planning software
https://www.skyhound.com/