If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on it instead.
Each additional Hardened Scales you control will increase the number of +1/+1 counters placed on a creature you control by one.
If a creature you control would enter the battlefield with a number of +1/+1 counters on it, it enters with that many plus one instead.
If two or more effects attempt to modify how many counters would be put on a creature you control, you choose the order to apply those effects, no matter who controls the sources of those effects.