I've found that blue packs are easily gained from games.

Work out when you can't win anything for the rest of the season, or if you have hit the objective you want and let the moral sink and just save the blue packs. Also remember that 2 blues used together will fill a players moral, regardless of how bad it was before - so never used just one blue pack at a time as its not the best way to get value.

Personally I've found blue packs quickly mount up. Ive over 1,700 of them and have never farmed any extra as I simply don't use them that often. If you can go a few weeks without using them I think you will find you will always have more than what you need.