There are some tips that can be really helpful for you.
1. To keep the bike engine healthy enough you must warm it up before getting the actual performance. If the engine is cooled down, that means if you are halting between some interval of time, more pressure lies on your car. The reason behind this, is due to the oil circulation. This is entirely different in Karizma in comparison to other bikes.
2. Put the choke for first 10 to 20 seconds so that the oil can travel easily to the engine. And remember do not leave choke for longer time, just for some seconds on start.
3. When you start your bike, after some time when the engine is cooled, due to lack of enough lubrication, more friction is produced and that caused damage to the piston.
1] Motul is a good brand. In most cases, stick to the manufacturer recommended grade of oil.
I think Hero Motu recommends 10W30 but some have used 20W40 too.
2] How To Improve Pick-up / Horse Power: Get Bangaluru's Joel's free flow exhaust and other performance accessories... Mail him at joel(at the rate of)raceconcepts.in. Joel is a MotoGP Engineer working for Team Ten10 Racing. So, don't get cheap exhausts from other places, it might screw your bike.
4] Rear Tire? You'll have to clarify what you need? Need Grip or power or size? A 120 section tyre should be good enough. Or Try getting the 130/70 from the new R15. Upsizing might result in more grip but lesser acceleration.
Also, you can make both tyres tubeless tyres
5] Sprockets? A 38 teeth rear P200's sprocket will reduce your acceleration and increase top end, or in professional biker's words: it will overgear your bike. Highway mileage & cruising speed will increase too. Do it only if you are ok with slightly lesser acceleration.
7] Plug? You can get a compatible NGK Spark plug, but it might give only slightly better mileage, maintenance, emissions, etc. but no noticeable power increase.
9] Chain: You can go for open chain for looks purpose, and use plastic (overchain) chain covers from P200/P220 or other bikes.
Don't mess with other things that I have skipped/ not mentioned. Because it might get you in problems or are expensive/ unnecessary.