Quiet as a cat's feet -- Brief Riki Guide

I have to disagree there. I don't think Riki needs to snowball at 6. I start to snowball once I get Difussal Blade, at which point Invis and Backstab are both maxed.
If you max stealth with an early point in smoke, you can lane safely, particularly in the offlane, which will get you your core items faster. Playing the lane-until-boots strategy I mention in the guide, you only need maxed Backstsab if you can't otherwise last hit.

The thing is, Riki has the highest base AGI in the game, so the faster you have it maxed the more use you can make of that fact. If you lane him solo offlane in pubs with max backstab like everyone else, level 6 lets you just flat out kill their supports. Then, hopefully you can buy HP and AGI items as you snowball out of control.

More early levels of Permanent Invisibility doesn't help you snowball. More levels in Smokescreen isn't necessary before level 8, because it's so strong at one point, whereas Backstab is not. How you get kills before level 10 is just blowing all your Blink Strike charges into the lowest HP, lowest Armor hero that you can find. If you go any other build, you just can't snowball early enough.

Totally man. I tried to make the point clear that what I was describing was my personal build, it's far from standard. What you're describing is a strong build for sure, but as I usually lane with a queue-mate as my support, I do like to force fights and smoke helps in doing so.
Even if I'm not forcing fights, it can and has saved my life, something backstab just can't do. One point in it at some point early on is just as good, so if you get it at level 3 and get backstab at level 2 I don't really see much difference.

As I mentioned, backstab definiteeeeeeely helps with last-hitting, which is something I can do anyways. If you can't, you should get it earlier.

I've got a few Riki games though I'm far from good and my experience is mostly from PUB games as I usually play something that synergizes better with team in team games.

While I like your build I'd possibly argue backstab is worth it at lvl 2 for easy last hits, as you probably won't be ganking with smoke at that point withotu a point in backstab (or maybe I'm just not good enough). I'd then agree with smoke on three and another invis at 4, but then I really would put another point in backstab. Blink synergizes so well with backstab it seems a shame not to have that and a 6 second escape is still "OK" at that point, even though 4 sec is of course better.

After that I tend to take another point in invis, then backstab, then invis until they're both maxed. I guess it's a build somewhere in the middle and I know in general it's better to focus on a certain style, but on riki it just seems to work for me.

It's intended to not be formatted. I wanted a quick guide to be skimmed rather than to be digested in its fullest. I've come across a few guides that did this and I found it easier to read than the copious skill/item icons. If more people would like a formatted version I will update it, but again, that wasn't the intention.

As for the skill order, I know it's not necessarily standard to build invisibility first. It's just my style, and part of my variations on the playstyle of Riki. If I just stuck to the vanilla way of doing it, I don't think I would've bothered with writing a guide...

Thank you for your positive words, though. Means a lot.

In fact, I disagree with the max Backstab build. It scales off your agility so leaving it until later when it actually becomes relevant might be a good idea. On the other hand, Smoke Screen is a potential 70% miss chance and an aoe silence that is far stronger than the backstab multiplier, in my opinion.

Not bad on the build, but you should have a look at the formatting guide: http://www.dotafire.com/dota-2/blog/dr-d/guide-formatting-and-you

Other than that, max Backstab is needed as fast as possible so that you can get kills. [Permanent Invisibility] at level one is the right build, and getting more helps you lane, but you can't forgo Backstab that long, or you miss out on your chance to snowball.

Otherwise, once it's formatted, nice build.