Hi,
If you are just visiting Dubai, then carry a little dollar with you. Rest you can take out in Dirham from the Airport ATM with a minimal conversion rate. Make sure, you take out enough because if you repeatedly use ATM, then a lot of amount will be simple wasted in conversion rates and bank charges.
For International travel, it's always advised to keep 2/3rd of money is $ & 1/3rd in Dirham (or local currency).
Reason: $ is easy to handle and readily convertible to local currency.
You should keep Indian currency for travel to & from airport in India.
If budget permits, you can have a credit/Forex Card as a backup
Thanks!