Here, we've got a variety of guides for people interested in MetaMask. Go ahead and check out the one that interests you:

• Advanced Usage for Users
• MetaMask Compatibility Guide for Dapp Developers
• How to get Ether Quickly with Coinbase
• How to check the MetaMask Logs

• Cause: When you install the MetaMask plugin, it is connected to a test network and can't get your account balances.

• Solution: Connect MetaMask to the Ethereum Main Net so it can get your real account balances.

• Instructions: Click the test network at the top of the plugin window and select Ethereum Main Net from the list that appears.

  

  This action logs you out of MetaMask. When you log back into MetaMask with your password, MetaMask shows the correct account balances.

• Cause: This is a known bug in Google Chrome / Firefox that appears in Ubuntu and some Windows builds.
• Solution:
  • For Google Chrome: A good workaround is to open the extension url, chrome-extension://nkbihfbeogaeaoehlefnkodbefgpgknn/popup.html, directly in a new tab and import through the tab.
  • For Firefox:
    1. Open about:debugging in a new tab
    2. Scroll down and find the Metamask {Internal UUID} (e.g. 12324c61-abc2-4922-a325-012697643ff5)
    3. Open moz-extension://{Internal UUID}/popup.html in a new tab and import through the tab