Welcome to the fun world of blink, jab, run, blink, jab, run!

Riki is is a very hard hitting hero with good escape mechanics. The key to this hero is patience and paranoia; although you have built-in invisibility, everyone will be making sure to turn that off so don't rely on it. Because you are relatively squishy, you will be a target; so you need to be very map aware when ganking and time your engagements in team fights around your offlane. Focusing the backline is typically riki's job as he can close the gap easily - and sometimes you just want to blink, tricks, smoke, and blink out to distract and harass while your team takes down someone else. You will go through three phases as riki: 1) early farmer, 2) mid-game fearless, 3) late game cannon; getting a feel of where you are at and transitioning properly is the key to success.

1) EARLY FARMER, until you have your your aghs and first choose one item, you should not look to hunt with the team; but, be aware of the enemy towerdiving and if you can punish them for it. With aghs, you farm fast and can reach a point where you are more open to participation sooner.

2) MID-GAME FEARLESS, if you achieve your first choose one item before 20 mins you will have more surviability than the other team expects (as most riki's go diffusal and then melt). At this point you can follow-up on initiations freely and should be able to blink out if things get tough or focus the backline - at this point you have great opportunity. Farming is still the priority; but, you can stick closer to your team to be ready for engagements which will launch you further. If the game is a stomp against you or your farm is slow, you may skip this stage and just keep focusing on catching up - using tricks in lane can help prevent you from showing up on the map while giving you good farm.

3) LATE GAME CANNON, this point of the game is achieved once you have both your choose one items and a late game item (typically by 30 mins). By now even though everyone hits harder so their coordination is much more punishing if they lock you down, survivability starts to dip a bit but is still good. Shutting down the back line becomes more important at this stage as well as making sure you have properly placed smokes. A single hero smoke won't cut it here, you should try and place your smoke to disrupt a core while cutting them off from support or disrupt 3+ heroes and then turn and focus the backline. Tricks is a good escape tool and avoidance tool for major AOE (IE an ES or tide ult) - it can also help you safely place your smoke as you can cast it while in tricks, then blink to the separated target.

Always assume they know you are there (don't rely on invis).
Burst separated enemies and if they try to group you can just tricks multiple heroes down.
Make the most of your smoke, a solo target will only punish you in the long run.

Have fun!