I have a few suggestions. The first and what I believe to be the most important is GMs and GSs need to make it a higher priority to ban or temp ban main accounts using alts for personal gain. I know GSs cannot ban, but they can see people using alts during gameplay, so more needs to be said to GMs. I do not believe there is anything wrong with having a shop character leveled to 30 just for the use of selling things the main has farmed in dungeons, but many people are taking the use of alts way too far. For example, people hatching baby angels, baby demons, bone dragons ect. for the Morph Crystals. Bone Dragon Eggs, Baby Angel Eggs, and Baby Demon Eggs are all 50 crystals. Someone could spend as little as $5 to put 500 crystals on an alt and hatch them to receive 11 Morph Crystals per pet. There is absolutely no level requirement to collect those rewards either. Nothing against cashers, as I am one myself, but there needs to be a level requirement to collect Morph Crystal rewards so people can stop abusing it with level 10 alts. If you are going to play enough to hatch cash shop eggs then you can wait until level 30 to collect the rewards.
My next suggestion is with Guild Daily Quests. There should be a limit on how many Guild Labor quests may be done by any one person. It is very easy to accept a guild labor quest and then farm the item needed for the quest so the next day you can do all 10 right after they reset.
The last suggestion I can think of is a medal exchange. I am short gold badges for my slayer gear, and once you are out of the level cap for Dragonspire, there are not very many ways to attain gold badges. Therefore, I think that so many bronze medals should be able to be exchanged for a silver, and so many silvers should be able to be exchanged for a gold.