In Battlefront 2, fanclub member, Jediknight D, discovered a secret that could earn you as many medals as you want (I'm typing this blog for Jediknight D because he isn't a hyperspace member and cannot write blogs):

First, go to the training (AKA the Attack of the Clones training level), because it has no reinforcements on either side. Then, do all the objectives until it tells you to kill 10 droids with Mace Windu. When that happens, be whoever you want like a soldier, engineer, sniper, etc. Go to the Geonosian hanger and wait for Geonosians to spawn. You can get many kills and medals. It's an easy way to get legendary on some medals, which lets you permanently keep the award it gives you like the elite rifle, beam rifle, flechette shotgun, etc.

Here are some ones that Jediknight D didn't tell me, but I thought of it:

Also try to make as many medals as you want before you capture the last command post like demolitions and technician.

Thanks to Jediknight D for telling us this.