I found a viable way to never have gold and ISO problems *seriously* must *read*
1. Be Uncollected
2. Spend one hour in arena every day
3. Change all battlechips from Uncollected BCs for gold/units
4. Save up to at least 3M gold and 2500+ ISOs (no ranking and leveling for 2-3 months)
5. Explore monthly quest from Beginner - Uncollected (2-3 straight month)
6. Rank up champs that are worth ranking. Garbage 4*s stay R3 max and Garbage 5*s stay R1 max.
7. Rank up 1-2 champs a week max.
8. Be discerning who you rank and level even if you're tempted to rank or level because of level up event
9. Continue doing 1-2 hours/arena daily
10. Keep doing as many quests as you can
It's been two months since I did this last May and I've ranked 2 R4 5*s, 3 R5 4*s and I still have 1M gold and 2000 ISOs left over.
You will only really lose gold if you never do arena and won't gain much ISOs if you don't do events as regularly as possible.
I hope this helps.