You can look into these steps:
- The number of participants you want to give.
- The opening price of your token and that is if you know how to control that on exchange. This is a thing you can initiate as the developer.
- As regards the amount to give @smyslov has already made a good suggestion, which is very common to most airdrop projects. Limiting the amount to be airdropped helps to prevent unnecessary dump. It's good to see that you have a reasonable supply.

I would also recommend you list on a reasonable exchange with good volume.