Commander #1610544 said:

I think i know how ops work, but there is a situation that generate me a problem. The game paid me a big reward. Then i lost largue amount of units and i cant get the units necesaries to reach a new reward. How should i act. Thx

I think it comes down to are you willing to buy units or to train them.

Buying units is quick and easy, you can purchase special offer packs or diamonds to train new units or revive lost units (revive is probably cheaper) and use them on special ops to get more rewards.

You can also train units relying only on resources you collect from caches/raids, take part in tournaments as well since they usually give units as reward. This of course takes time to build up.