Re: No "Newbie guides"!? shoutout to all the experienced "ol
A good point you are making as a beginner. Bikes are a mature product, and probably like a lot
of people you will simply pick-up things by getting stuck in and simply working on them and riding them.
Repairing a puncture would be a good start
There's good resources mentioned above to help with the mechanics, but to help with these two points I'll offer some general advice / opinions:
- Recommendable brands and types, like what to get and what to avoid
- a buyers guide, like what to look for on bikes to estimate the quality and functionality of the bike
Rightly or wrongly, but that's the way it is, the bicycle industry is a fashion driven industry. The latest and greatest sells, and this pretty much boils down to making things lighter and stronger than the version before and adding a few gizmos here and there. This general rule pretty much applies to every price point and
every period in the development of bicycles you can imagine.
As such, it's very difficult to make a good compendium of what
really is good and bad because there are so many varieties and so many opinions and so many different requirements the bike owner expects from the bike to serve a particular purpose. For example, you could start a war here by asking the age old
question if Shimano is better than Campagnolo. I will say though, avoid Sachs-Huret rear mechs, they suck

.
Seriously, a good pointer is to study a manufactures bike range for a particular year and the associated original RRP with this site
http://www.bikepedia.com/ or some of the original catalogues in the archive.
You will get a reasonable understanding of what was / is high-end kit verses low-end kit.
Finally, don't always assume because it was expensive years ago and now that it's old means
automatically it is good retro gear; there was a fair share of useless crap too which hopefully found
it's way to the tip and retro pricing is more about how
desirable the item is. This site as it all,
and it's best to ask on a case to case bases. Using the Ebay "completed listing" functionality will give you a good idea of what the
real worth is for pretty much anything; rather than subjective or inexperienced
personal opinions.