How should I practice close-quarters fighting with Rengar?

I had this problem while starting Rengar and found a few things I did over time helped.

Step 1: Practice combos on bots.
To clarify, I do 3 things with Rengar. I check his bar to see if the next skill queue/combo will proc ferocity, I check to see if the trade is worth(review their items and mine) and lastly I figure out what kind of trade I want it to be. This ranges from starting e(to catch them) or using the bushes to grab on them and chase them while they're slowed with e.
Step 2: Keeping track of your ferocity.
One of the best ways to avoid losing track to keep an eye on your ferocity. I use a counter after the 3rd stack unless the fight is drawn out.
Step 3: Turn off auto attack.
Turning off auto attack in the menu options can be really helpful. The feature can cause some error or difficulty with certain champions and as a result, it's better to practice without it to gain a better understanding of your champion.
Step 4: Auto-attack canceling.
Your skills can be used in coordination with autoattacks to maximize your damage and minimize the time you need to perform a trade. Practicing this can be very easy on waves and cs.
Step 5: Watch streams/LCS.
This has been critically important in my development as a Rengar player. When watching the streams, pay attention to the slight choices that players make. Their builds can be very situational but the casters tend to explain anything out of the meta to the audience. I'd advise these over youtube videos as most of the videos are outdated. (Ex. Build brutalizer into black cleaver instead of what is currently live; phage into black cleaver)

Rengar is a very easy champion to start with, but he's very hard to get good with.

On another note, that anxiety you get when using his ultimate can be approached 2 different ways. You can harness it and learn to focus during the stress to perform better under stress, or you can learn to calm down when using it. To relax myself when using Rengar's ult, I assure myself that it'll be back off cooldown especially when I build tons of CDR on Rengar.

That stress you can get can be very useful as it keeps you aware and alert, utilizing it can be thrilling and rewarding.

Slow down, try out in customs, get the combos right.

I am a rengar main ever since season 4 began. So I guess I have the authority to speak here. The main purpose of rengo's ferocity bar is for you to maximize its use and choose wisely that skills to use with the ferocity effect. I will teach you a little combo I ALWAYS use. You may have seen rengo lovers like Nightblue3 or 13imbi on Youtube abuse this AWESOME combo. its (in order) 1. Get 5 stacks 2. activate Thrill of the Hunt 3. activate ghostblade (the item) 4. when nearing the victim, activate q, if done right your ferocity bar should COMPLETELY deplete and you're about to leap 5. click on the target to leap, (rengars q can be hit mid leap or before the leap as long the leap is completed before q duration ends) 6. alright, rengo's leaping in mid air, press e before you land, like when he's on the air, if done right rengo should switch to e animation before landing 7. chill, you've landed now this is where you USUALLY make mistakes right? alright, after landing like on the first frame rengo's feet actually met the ground, you tap your w and tiamat at the same time, this is called an animation cancel, 8. good job playa, you've landed and you now have 2 ferocity, now activate your q one last time to finish the kill.

done! here is a video to help you further:https://www.google.com.ph/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwjK9cjZ5K_JAhUGsJQKHTpwAWkQtwIIHDAA&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DS2wdXgBeqEc&usg=AFQjCNH8nS9RCSclN4f9uNO2hNucGU2m6g

but we don't end here, I wouldn't want you using the same one shot combo all the time! we have two more!

this one is the empowered bola combo, which is waaaay easier. Use this one for ganking because if this is done right, you will dominate!

1. activate ult with five stacks
2. click on enemy when in range and bola mid air. if done right fero bar should be COMPLETELY depleted
3. q + w tiamat combo, also, remember you can cast q and w at the same time.

and the final combo probably more stylish than the others I call this the AP RENGAR combo!

1. activate ultimate, 4 stacks
2. activate q, if you have lich bane then it should turn purple, you should have 5 stacks before you leap
3. now that you have five stacks, click on target and annihilate them with your w+w combo
4. follow up with e to last hit

I hope I helped, let's rek the shaco mains, one one shot at a time. Keep praticing these combos, play reaction time mini games to enhance your tapping speed. Don't stop improving, for a true hunter never rests.

Here are some things you can do to help your CQC:

• Keep calm and don't spam, instead, try to be more accurate and precise
• Test out the combos in custom games
• See some Youtube videos about Rengar
• Research the various item builds

Also, make sure to unlock your screen. You can't play jungle without it. (assuming you are using Rengar as a jungler) If you do this, you'll probably master it within a week. Try to play as Jungler.