Becoming proficient at bike mechanics- where to begin?

You download an official workshop manual from many forums, or you buy one on CD from ebay.

I got one for my GSX-R 1000 K5 from here

To the original question, as I’m sure has already been answered, to learn, get a crap bike (I used a Peugeout Speedfight 2 scooter) and buy some cheap tools from like a pound shop.

Download or get a service manual off ebay.

When you get into it, replace the tools that break first with higher quality items. These will be the tools that you use most often.

It teaches you a lot being able to work on your own bike and means that even if you take your bike to a garage, you’ll be more likely to spot if they take any short cuts in servicing it.