From my experience gaining reputation is simple yet hard:
1, Keep the node online
2, Don’t loose data
This is from my experience High uptime means the satellites can access the node easily this should grow the reputation. Not loosing data is another important point loose too much data and you will be disqualified from satellite once this happens you will not be able to receive data from that satellite again. And lastly AGE, The older the node gets the more time it is the more mature it is. Simply put it can be seen as more reliable node as it has been with the system for a longer time.
Please do not quote me on this. This is just my experience over some time. there might be lots more metrics which I suppose there are. But these are the 3 points that I came into contact in my experience.