Lists:

First things I do on a fresh net-cafe Firefox install:

1. Hide the Bookmarks Toolbar (View > Toolbars > Bookmarks Toolbar (uncheck).)
2. Turn on Find-as-you-type (Tools > Options > Advanced > Begin finding when you begin typing (check).)

Sounds that gave me a hard time when I started learning Chinese, but are no longer a problem:

1. Pinyin 'r'.

Sounds that were no problem when I started learning Chinese, but now give me a hard time:

1. Pinyin 'e', whether it makes different sounds in 'en' and in 'meng'.