Everybody has their own squeak, rub, or creak story. Here's a link to a website by Jim Langley.
Always carry at least one spare tube when riding - consider carrying two if riding alone. You'll also need a repair kit including tire irons and patches. All the local bike shops have these inexpensive accessories. You may want to carry a spare tire on multi day tours. It goes without saying that you'll need an inflation device. While CO2 inflators work well, they're one shot devices, so always carry a small pump.
Washing your prized possession frequently is the best way to keep it in prime running condition. A dirty chain and cassette cause premature wear on these parts, which can be costly to replace. Clean often and ride smoother to ensure a longer life for all your bikes components.
If you're not comfortable with messing around with your shifting, by all means take it to one of our local bike shops. A simple indexing only takes minutes. MEC and Bushtukah frequently offer free bike maintenance workshops where you can get professional instruction on how to index. If you continue to experience bad shifting performance, check your chain length. A "stretched" chain often shows up in poor shifting.
Having a good wrap on your bars not only looks good, but can feel good too. The extra padding and grip of a fresh wrap is well worth the effort. Regardless of colour or type, there is really only one wrapping video to watch.