I was asked how one contributes to standards. Before anything else, it is worth watching Domenic Denicola’s presentation on making friends and influencing standards bodies. It is awesome and will teach you a great deal.
I think the core thing to understand when considering contributing to web standards is that they are created by communities. Typically there are a few people leading the charge and many people contributing with critique, research, and tests. Usually there is a combination of mailing lists, IRC, and the occasional face-to-face meeting, to keep everyone roughly synchronized.
A lot of discussion still happens through email and given the volumes you need to filter it to some extent. An effective way of doing this is by paying more attention to the peers you know and trust and checking from time to time to see if that list of peers needs adjusting. E.g. if you follow the development of JavaScript you want to read email from Allen Wirfs-Brock and Brendan Eich. If you follow development of HTML you want to read email from Ian Hickson. You’ll quickly find out Boris Zbarsky is insightful irrespective of the mailing list involved. If the people are not immediately obvious to you, you can always ask on IRC. These people will often reply to the key points within a thread and make it immediately obvious what it is about and why it might be worth paying attention to. That way you save yourself some time reading the whole thing. Of course you will need to judge for yourself how to filter, but some amount of filtering will be required if you want to keep up with the community and also do some work.
You want to figure out what community to participate in:
Unfortunately there’s a myriad of other smaller lists for particular APIs. Usually the standard you care about has relevant pointers. If it doesn’t, please file a bug or let someone else know as it definitely should.
Studying the output of the community (the standard and tests) and its ongoing progress (the mailing list) is a good way to get a feel for how things work and what you should pay attention to. It can help to read the WHATWG FAQ too as it documents answers to many common questions. Having familiarized yourself with the material and the environment you should feel more than ready to start participating more actively, in particularly if you see something worthy of improvement.