Certificates
Certificates are an in-game currency I earn for completing missions in Goodgame Big Farm. They aren't a resource I harvest from a field or produce in an animal building, but a reward tied purely to finishing tasks. The only use certificates have is building and upgrading the farming machines in my garage.
I see certificates as a currency that pushes me to do missions regularly rather than in bursts, because otherwise a build or an upgrade in the garage just sits there waiting. It pays to keep them topped up alongside normal play instead of scrambling for them the moment I need a machine.
I get certificates for completed missions and there is no other way to them

I get certificates every time I finish a mission, whether it's an ordinary daily task or a mission tied to the farm's story. I don't produce them in any animal building and I don't harvest them from fields, the only route to certificates leads through completed tasks.
What works for me is treating missions as a steady source of certificates rather than a one-off chore I clear and then forget about. The more regularly I do missions, the more certificates pile up without me having to pay any special attention to them.
I spend certificates on building and upgrading machines in the garage
Certificates have one specific use, they go towards building and upgrading the farming machines I have parked in my garage. Without them I can't get a new machine or an upgrade for one, no matter how well sorted I am on other resources or money.
The garage is therefore the only place certificates ever end up. Before I start building or upgrading a particular machine, I check how many certificates it takes and plan how much longer I need to keep doing missions before I get started.
I would rather save certificates for one specific machine than spend them at random
- There's no other way to make or buy certificates, so I'm careful with how I spend them
- I decide in advance which machine in the garage I want to build or upgrade first and save my certificates for it
- I keep doing missions even when I'm not building a machine right now, so certificates don't pile up in bursts but are always there when I need them
