Bitcoin is a protocol that was born from a small community and has grown fast since. There are a lot of things you can do to help Bitcoin to spread and improve over time.
Using Bitcoin is the first thing you can do to support Bitcoin. There are probably many cases where it can make your life easier. You can accept payments and make purchases with Bitcoin.
Be the network
You can join the Bitcoin network by keeping full node software running on your computer or dedicated server. Full nodes are securing and relaying all users' transactions. They can be compared to the backbone of the network.
You can start mining bitcoins to help processing transactions. In order to protect the network, you should join smaller mining pools and prefer decentralized pools like P2Pool or pools with getblocktemplate (GBT) support.
You can help to increase Bitcoin availability by translating or improving translations inside important parts of the Bitcoin ecosystem. Just pick a project you would like to help.
Bitcoin is free software. So if you are a developer, you can use your super-powers to do good and improve Bitcoin. Or you can build amazing new services or software that can use Bitcoin.
The easiest way to help is to donate a few bitcoins to the Bitcoin Foundation. Or you can help directly fund any project related to Bitcoin that you believe will be helpful in the future.
The Bitcoin Foundation and many other non-profit organizations are dedicated to protecting and promoting Bitcoin. You can help these groups by joining them and taking part in their projects, discussions and events.
Speak about Bitcoin to interested people. Write about it on your blog. Tell your favorite shops you would like to pay with Bitcoin. Help keeping merchant directories up to date. Or be creative and make yourself a nice Bitcoin T-shirt.
Meet the communities
You can join Bitcoin communities and talk with other Bitcoin enthusiasts. You can learn more about Bitcoin every day, give help to new users and get involved in interesting projects.