[Master Batter]

I have a basic understanding of programming principals as well a rudimentary knowledge C and Lua.
Learning Sourcepawn also seems like a very achievable task, however the source engine is such a huge
and complicated thing I was wondering the best way and where to learn it. Should I specialize in 1 specific thing? (Server Plugins, hl2 mods, maps, gmod stuff etc), and what are some good resources to learn with? I just don't know where to start!
For context I have made a few (pretty bad) maps for tf2 using hammer and some command line programs with C and lua.