Upgrade sources - newbie

[Darren Wheatley]

Hi,

I'm new to Ubuntu, and Debian.

I have heard a lot about apt-get and how it is easy to install and upgrade
software.

I have installed Ubuntu and have uncommented all the sources in the
/etc/apt/sources.lst file.

I have lots of new software that I can install and upgrade!

However, I'm not sure what to do...

If I run a general "apt-get upgrade" or whatever the command is, will it
install lots of "universal" unsupported stuff? If so, is this wise?

How do I keep my system as up to date as possible but as stable as possible?

Any help, suggestions, pointers to book and web sites would be appreciated.

BTW, I have been using other distros for years and have a lot of technical
experience so I am happy with technical docs.

Regards

D.