To get level 3 asap use this clear path. If you are starting blue buff, go blue->wolves(smite the big wolf)->3 baby raptors->red buff.This way you will most likely get an level advantage against the opponent jungler if they were to contest for scuttle crab. Play Video

The first back is dependent on the opponent jungler. If you are against a champ with a fast and healthy clear, opt for a sabre. If you are ahead/confident in your ability to out jungle the opponent and efficiently use the extra cdr to your advantage then go for the warhammer. Also if you end up getting a sabre, make sure to grab boots if you have enough gold for increased map pressure. Control wards are a must, if you have 75 or more extra gold then buy it. The control wards can help you get an abundance of information in the jungle, as well as set up for lane ganks/counter ganks.

You almost always want to rush warriors as your first item. The usual item sequence for riv jg is to rush warrior, build kindle and warhammer for that 40% cdr(Warrior + warhammer + kindle gem + transcendence = 40%cdr). From there on it depends heavily on the opponent team composition and what your team needs. If your team is lacking a bruiser/semi tanky unit then you should go to for the black cleaver. If your team is lacking proper damage then opt for an immediate dusk/ghostblade after completing warrior{Do not get kindle gem in between warrior and dusk blade].The hydras fall within the same principle as well. If you need more damage then go for Ravenous and if you need more health/tankiness then go for titanic. Edge of night is an situational item, if they have a lot of tools that can deny your engage then get it. Guardian Angle is almost always an great mid/late game option, it gives you more survivability and opens up for riskier plays that requires you to hard engage. If you end up going for warrior->cleaver and left with a warhammer, in most cases deaths dance is a great option. Storm razors a fun item, build it in norms.

The boots are pretty straight forward. Against AD heavy comps go for Tabis. Against AP heavy/CC heavy comps go for Mercs. If you are in a need for early cdr then go for lucidity boots, however make sure you sell these late on to the game and get different boots since you most likely will end up with more than 40% cdr at that point. Selling Lucidity later would not be gold inefficient because of the early summoner spell advantage it gives you. If you can get a big play/advantage off of the extra 10 cdr and your SS advantage then it is more than efficient.If you are extremely ahead then opt for an mobility boots for maximum map pressure.

Always go for fleet footwork. The healing this rune gives plus the attack speed the precision tree gives will greatly help Rivens jungle clear. The movement speed helps you disengage faster after attacking the enemy champion as well as make your tempo in the jungle faster. Transcendence is an obvious one, Riven needs cdr. Take water walking for scuttle crab control and river skirmishes. You can take nimbus cloak for extra chasing power but it is not recommended.

Pros: High mobility and Multiple CC makes her a great ganker.
Her scaling is very good.
Her build is not limited, she can be an assassin/bruiser/Even a tank depending on what
your team needs.

Cons: If you are not used to playing her you will struggle clearing the camps, hence slowing
down your clear tempo and delaying your ganks.
Weak to early invades since she does not have any sustain tool in her kit.