Has anyone been working for Google or has experience interviewing at Google? Could you share any tips or guide from preparing for resume to interview?

You can try connecting with employees from Google with similar interest/same alma mater on LinkedIn. From there, you can ask them about their experiences, processes, and advice. If you feel you're going rather well, you can ask them for the hiring manager's profile or a referral. Usually, companies have incentives for each sucessful referral. Also, remember to reciprocate with either a meal or something you're able to benefit them.