Agree with previous posters that your life (and back) will be much easier if cot has one drop-side and two adjustable heights for base - as mentioned high for bub and lower for standing child.
The drop-side should be easy to operate with one hand (as you wil often be holding bub) and have no dangerous clips or anything that can catch the child.
Not sure what safety standards they have here but maybe look up the Aust or UK ones for cots so you can have some good info. Look at standards for spacing of bars as can't be too big for bub to get stuck. Shop should be abel to tell you what country standards the cot meets.
If cot has castors on legs for moving it around make sure it is only on two or that there are brakes if on all four.
Make sure mattress fits snugly with no more than a 2.5cm gap between mattress and cot on all sides (again don;t want bub getting stuck).
And of course for SIDS risk you should never use a cot bumper or have cushions, pillows, large toys etc in cot with a baby.
If buying a painted secondhand cot check the paintwork for chipping and possibility of lead-based paint having been used (depending how old it is and where it is from).
Not as hard as it sounds as many cots will be suitable and you will end up having the hardest decision being making up your mind which one you want!
