Don't know about 3rd but I got my TRV in second attempt.
What are the reasons of denial? We were refused because of 2 reasons: no travel history and VO not satisfied that we will return back to India. So we re-applied with as much as supporting documents as possible and a strong cover letter, explaining why we dont have a travel history and that we will return to India.
By supporting documents I mean affidavits from employer, friends and family vouching for your credibility and an affidavit from myself, stating that I will return back after a given duration without fail.
Basically you need to satisfy the Visa officer that you are a genuine person and a law-abiding citizen with enough ties to India to come back. Since they dont interview you, your cover letter is the one document they judge you with, so add as many details as you can in it, my cover letter was 3 page long