There is no long list that you can follow, as Samsung devices are running on Touchwiz, which itself is RAM consuming. Still you can go with following.
Remove Samsung or google apps that you dont use ( playmovie, SNOTE, Galaxy apps etc ) from your device and if it can't be uninstalled, disable it.
Remove RAM cleaning and security apps like RAM CLEANER, 360 Security, RAM BOOSTER. These apps are worthless as it does not help to clear ram instead app itself run in the back ground.
Use lite versions of apps rather than full version. It will consume less ram.
Remove empty folder from your Phone Storage and Memory Card. ( Not from the Android and data folder )
Use apps other than stock like you can use QUICKPIC instead of Gallery. It will make some of your work faster, as these apps are of few mbs, but blazzing fast.
Use faster Memory Card, and dont fill Phone storage and memory card to its limit. Leave some space.
If you are pro, then you can root your device and install custom ROMs, it will make it fast. For rooting and all stuff you can visit, developer.com site. Its heaven for Andoird developers, and everything related to android develpoment and all stuff.
Disable some functions from the settings> apps, like air drop, smart screen, screen mirroring if you are not using it.
Do factory reset in case if you feel your phone is full. And so much to delete.
Use latest version of android. I.e check for regular update.
Hope it helps.