Treat each Google service...
I've always treated each Google service as a separate service each with it's own account. In fact, that's exactly what most of them were originally.. Log out after using each service. Log in to each service with a unique username when you do need to be logged in.
Yes, you will most likely be coming from the same IP address, but that's also the case on shared PC's or NATted home networks, which is probably the majority of households. They don't k now if it's "you" coming from that address with a different username.
This can't stop them tracking you doing this, but it can make separate and disparate trails which, in their eyes are probably different users.
As someone who has been on the 'net for many years it's natural to have different log-ins for different services, but the facebook generation will see a consolidated log-in as a benefit and be happy to give away some privacy for micro-second of extra convenience.
We are already seeing stories of people failing to get jobs because the prospective employer has trawled the 'net to find out about he prospective employee. This should be a huge big red flag to all to keep web activity, log-ins and usernames discreet and separate on different services. In some case, keep two separate accounts on the same service, one you don't mind people knowing about, one for your drunken ranting tirades ;-)
FWIW, this username is unique to this forum. You won't be able to match comments here with anything else I may or may not have done on the 'net. The site admins might, but your average prospective employer won't.