3 Separate Ways to Terrorize your enemies
3 Core Builds
3 Ways to Attain Rikimaru's Maximum Potential

The following guide will foreshadow what is to come in your later games with the intriguing Riki. I will show and teach you all the ways that I have played around with to get the ultimate killing experience with various builds. Here's how it goes:

To start, I should probably tell you which items I prefer.
1. Items - One tango of 3 stacks, One Healing Salve, and last but not least two Slippers agility. By the first 15 min you should have Two Wraith Bands, Poor Man's Shield, and a Quelling Blade. Later on you replace Poor Man's Shield for something more valuable along with the Quelling Blade, and even later replace the Wraith Bands with the below items:

Items cont. - I usually play Riki with 3 unique builds and these are my Safe build, Damage Build, Agility Build
My Safe Build consists of : Power Treads, Two Wraith Bands, Sange & Yasha, Vladmir's Offering, and the infamous Diffusal Blade. If enough time is given then replace one of the Wraith Bands with a Butterfly and the other with anything of your choice (I usually prefer Black King Bar)
My Damage Build is a rather risky setup but I like it due to the heavy damage output and its unique sense of play-style. This build consists of: Power Treads, once again, two Wraith Bands, a nice Stygian Desolator, Daedalus, and a Vladmir's Offering for some life-steal. If enough time is given then replace the Wraith Bands with a Black King Bar and anything of your choice (In this case I like to have a Heart of Tarrasque)
My Agility Build is rather similar to my Safe one. It consists of: Power Treads, two Wraith Bands, Vladmir's Offering, Etheral Blade, Diffusal Blade (If enough time is given, replace the wraith bands with a Butterfly and a risky but useful Eye of Skadi)
Keep in mind, the Power Treads in all these builds should be set to Strength for maximum survival.

2. Spells - This is perhaps the part in which I am most criticized for. I put myself in this position due to my avoidance of Smoke Screen till Level 10. This may sound very dumb to a lot of people but here is why I do not pick that spell.
I find Blink Strike and Backstab A LOT more necessary for early farming and killing. The combo of 4 Slippers of Agility along with Backstab fully maximizes your Agility and it results into a lot of damage. I sometimes maximize Blink Strike instead of Backstab and at other times I do the opposite. This usually depends on my enemies that I face on a certain lane. Max Blink Strike against Ranged heroes as it will be very handy in escape situations while Backstab is more valueable against Melee heroes in harrasment situations. Of course, right away at Level 6 you must put the point obtained to your ultimate: Permanent Invisibility as it is what defines The Stealth Assassin. Once Blink Strike and Backstab are maximized, then is the time when you should start to put all the following points from Levels 10-14 to Smoke Screen. Level 15 is the first time when you should use a point on Extra Stats. Level 16 should be the final point in any skill while, if enough time, the rest of the points go to Extra Stats.

3. Playstyle - I do not like to sound cocky but I've noticed that my Riki playstyle is quite unique. Immediately at Level 6 I become a very painful adversary to the Dire/Radiant as I do not give my enemies a single moment's rest. Using the advantage of my Permanent Invisibility and Backstab along with my Agility items, havoc is unleashed upon enemy heroes with every single strike due to the gigantic damage output at the given level.
I like to spend a lot of time farming in my lane and harassing other heroes as much as possible as this is how the rest of my game is determined. Focus a lot on how to gain loyalty from your enemies and wait patiently for when to strike. Playing Riki requires patience and I always like to think of it as a ;kill or be killed state of mind; Harassment is the key to victory and unleashing such harassment may result into you getting ;fed; and the out-farming of any adversary which will surely gain your team the victory you so rightfully deserve.

4. Have Fun - Riki and Invoker are perhaps the most unique heroes in the entire game and my success rate is highest with both of them. They get me what I was supposed to obtain from the game in the first place: Fun!
If you would like to terrify your foes follow these simple steps and I will guarantee you will win many games ^^. I myself have 26 victories as Riki and its my most played and most successful hero.
I hope this guide will help newcomers to the game and I also hope they can see the true power and potential behind this hero

Enjoy :)... Now go own some noobs!