Learn a scripting language. Java, C++, and C# are great tools, but a command of scripting languages will serve you well. Perl, Python, and Ruby are the perennia

Learn a scripting language. Java, C++, and C# are great tools, but a command of scripting languages will serve you well. Perl, Python, and Ruby are the perennial favorites - I prefer Ruby, personally - but there are tons of others, like Lua or Javascript.