A few newbie questions about manual shifting and car maintenance from a new VW purchaser?

I bought a certified (yay!) pre-owned 2003 VW Jetta Wolfsburg Edition. It’s turbocharged with a 1.8 liter engine. My question is this: I have never cared (due to the general “junkiness” of my previous manual transmission cars) particularly when to shift, seeing as how I usually just listened to the engine as to determine when [...]