How to prepare for CAT properly???? What should I do in the beginning ?? Which coaching should I join?? I'm living in Jaipur .

Hey !
Firstly talking about preparing for CAT, look at the competition a seat has in the top B-SCHOOLS like IIM's (especially IIM- A,B,C). It's almost 2.5 lakh students competing for 4000 seats in 20 IIM's. I guess it's clear that you need to prepare right from the time when you aim at CAT. Preparation tips include
1) Firstly knowing the pattern and difficult level (according to past papers at least you can get a rough idea of what it's going to be like)
2) Knowing  Duration of the exam and concentrate on your time management skills.
3) Speed and Accuracy is the most important thing which when done well can end you up with high percentile.
4) Taking mock tests( frequently) once you are done studying all the basic concepts of Quantitative aptitude and others can help a lot.
5) For a good CAT percentile, preparation can require time anywhere between 8-18 months.
In the beginning, start with knowing all the concepts instead of taking too many mock tests.(basically in the first 2-3 months), then in the next stage practice problems in the concepts you are done with (mostly in the next 4-7 months).
In the last stage when you will be perfect in the core concepts
start taking mock tests so that you can attempt variety of problems and learn them if you missed any at the time of preparation.
Coming to coaching, if you don't have time from your daily schedule i.e if you are studying or working for Long time then prefer taking online coaching. (According to me online coaching and self preparation are one and the same, it is just that online coaching gives you series of mock tests to practice. But still in some ways it's better to take Coaching if you are attempting CAT for the first time). For offline Coaching there are many good institutes. As you mentioned Jaipur, here are some of them :
1) TIME
2) IMS
3) Career launcher
4) PT Education
Check the below link for more info regarding CAT
https://bschool.careers360.com/articles/cat-preparation-tips-for-beginners
Hope this helps
All the best !