Many travellers making the pilgrimage to Akiba take a path starting at Shinjuku, the world's busiest rail station, and arriving via the Chuo or Yamanote lines. If you're in Shinjuku, you can take the Chuo express to Ochanomizu and cross the platform to the Chuo local train. Akiba is one stop from there.
But, a word of warning: if you arrive via the Chuo line, by all means do NOT go to the curry shop pictured above! It is overpriced and will make you barf! This shop should be renamed "NEW RIPOFF AKIHABARA"... for that matter, you should take my advice and just avoid eating curry at shops inside rail stations in Japan, period. You'll always regret it later.
Avoiding the curry shop, we roll merrily down the stairs, through the occasional throngs of people, past the automatic ticket machines (you did buy the correct fare, didn't you? If not you can fix it with that machine over there) and exit the station.. to...