(7.29 - Necronomicon is no longer a thing. This is a blatant attempt to bring down the power level of this build)
Things have changed. Wards are free, and couriers are bought automatically.
Evidently, Valve wishes to cut down on the power level of this strategy, but don't worry; it's still as strong as ever.
Now, without further ado,

Vision Officer Riki is an unusual build in which you forfeit the fifth member of your team in favour of a player to control all things vision-related, for the convenience of the other players.
Riki can do this excellently due to the fact that he's essentially a mobile ward.
In this build, you will buy all things vision-related including many wards and many living-ward summoning items.

Previously, I had stated that Vision Officer Riki has no place sucking up lane experience. However, now that his invisibility is on his ultimate, I advise staying in lane until level 6, at which point you should forfeit further lane experience. You are still forbidden from taking last hits, however.
After this point, you must farm the jungle as best you can if you want any chance of affording wards and other vision items.
Unfortunately, there is not enough money to buy jungling items, so you'll have to try your best, and make stops back at the base if you get low.
You should also be the first on the scene to grab bounty runes with your invisibility. They will provide a lot of valuable gold.
This build is designed to be used in place of a jungler or offlane support.
That is to say, DO NOT SUPPORT SAFE LANE WITH THIS BUILD, otherwise your hard carry will hate you.