Starting as Scrum Master

Neha,

Good to know about your interest in Scrum. I have found it very effective for software and non-software projects.

I understand that you've done SM certification - that's a good starting point and as you are inquiring - working as a team member in a Scrum team is the most effective way to learn.

If there is an opportunity in your organization where Scrum projects are executed, jump in!

Yes, jump in, start pulling the problems in a Scrum team and solving them. While this is an informal way to get an entry in a Scrum team, your senior management will look at it as your leadership quality.

I am sharing this advice because I did so way back in 2008 when I did not even have a Scrum Master certification - and management of my organization recognized it as a good leadership quality and helped me in gaining practical experience using Scrum. Eventually, I took the certification but I must say that the earlier practical experience I had contributed a lot.

Also, to be successful as a Scrum team member, you must be ready to lose your individual title and start working as a servant leader who solves the problem. I wrote this piece of article in 2012 which might be helpful to you: https://www.scrumalliance.org/community/articles/2012/may/seven-things-…
(there are lot of comments and criticism on the article and you'll see different point of views there)

To me, Scrum is entrepreneurial by nature. If it is an employment and the senior management does not see value in it and does not buy into Scrum as a concept, it is difficult to succeed as a ScrumMaster. In those cases, you might look for organizations where Scrum practices are welcomed.

could anyone suggest the best book/course material for preparing PSM -I. I have just completed foundation level certification.

Read the Scrum Guide, over and over again. At least 15-20 times.
Take the Open assessment tests - all that are available!
Read blogs - Ken Schwaber, Mike Cohn + any other ones of interest!
Read forums like this - see what are the real world problems and how scrum might go about solving them.
Contribute to the forums and ask questions - people are always willing to help out.