@mohdabbas , from a personal experience, take a test ride on both YBR and YBR-G models, whichever you like the most. Like a friend of mine said "Bike woh lo jiss per dil aye, baqi logoan ki batayn chor do".
Secondly, Buying new? Make sure the seller is authorized by Yamaha , go to their website and see a list of authorized sellers. Be careful of part-swaps, it's pretty common on small showrooms in Karachi, so agar 500 bhee ooper denay parayn, go for a better , well reputed showroom and buy from them. Make sure the vin/serial number on the chasis matches the one in the book (duhh).
Other than that, I would say brand new means brand-new, like zero meter, not a showroom model or one with 100 km on it. When you buy, follow the proper running period up to 1000kms by the book, and get your service done.
Regarding service : Make sure the guys are not messing with anything other than oil-change and basic maintenance like air-filter cleaning and oil level checks/lubrication. So "sar pay kharay reh kar karwayen".
Hopefully other guys will chip in their knowledge too