I am having issues getting coins, the 50 or some times less received from gyms is just not enough, any suggestions on getting more?

Tips:

-Master the art of finding and defending optimal gyms.

-Pace yourself to avoid wearing down all of your Pokemon. Sometimes it's best to pass up an enemy gym or a raid.

-Spend gold on clothes, space, and passes instead of items that can be found at a Pokestop or gym.

-Work toward a gold badge in at least one gym with a reasonable level of competition in order to gain better items from it.

-Manage the space in your bag to avoid needing to expand it.

-Use wild caught Pokemon with a decent cp level as pawns before tossing them out. This will give your main Pokemon a break and help save valuable healing items.

-Consider clearing level 1 or 2 raids if you have free passes to spare.

-Don't forget you can earn one free pass a day and hold one pass which means it is possible to use two free passes in a single day.