From what I know, SSL encryption is relatively safe in itself, but ISPs can pull tricks such as was done in Egypt:
http://www.theregister.co.uk/2015/03/24/google_ssl_cnnic/
There is much literature on that and I'm not sure about details anymore.
Certificate authorities can issue certificates which can be used to set up transparent snooping for users.
There are safeguards in place, and even more since that happened. Google seems to be behind some efforts, and using Chrome should be an OK option.
If you are doing something sensitive try using Tor (on a live disk, not to leave traces in your cache, etc.), hopefully it's not too slow.
In the end there is no substitute for being an advanced user and knowing what you are doing, but encryption and security is a complex science.