IIFT conducts its own entrance test while for XLRI you need to appear for XAT. All other colleges like FMS, IIMs accept CAT scores only. All these are difficult entrance tests on their own, so focus on getting a good percentile in all the entrance tests in the first place.
After getting a good percentile, getting calls and eventual conversion depends on a lot of factors including past academic records, work experience, and GD/PI performance.
Ultimately past academic records, work experience you cannot change. The only thing in your hand is your CAT/XAT/IIFT percentiles and your GD/PI performance. Focus on getting as high a percentile as possible.