How can I receive the maximum number of premier balls?

Solution 1:

According to the PokemonGo Hub, a data mine revealed that the following influence how many Premier Balls you receive:

• The base Pokeballs
• Your damage contribution
• Team Damage contribution
• Gym Ownership
• The percentage of damage inflicted by your team

All of these seems to hold true based off the screenshot in your picture. One source suggests that the level of your Gym Badge with the gym influences how many you can receive as well.

The Silph Road Reddit seems to agree with this list, and states the same, with the addition of a currently unknown multiplier:

In a Raid, you appear to be awarded more 'Premier Balls' based on a few factors. These include:

• The base Pokeballs
• Individual damage contribution
• Team Damage contribution
• Gym Ownership
• The percentage of damage inflicted by your team
• A 'Bonus Item Multiplier' (unclear at the time of publication)

I think it's pretty self explanatory on how to receive more premier balls. Basically, do as much damage as you can, your team has to do as much damage as they can, and try and do Raids in Gyms that are controlled by your team.