1. Dont go solo dungeon :D
2. The maximum level distance between the highest and lowest level players is 5 levels, otherwise there will be an EXP penalty.
3. Make sure in your team have healer (QuantumFixer) and damage dealer, more damage dealer is better.
4. Make sure to stay within 200 meters of each other, so you can still get EXP when monsters die.
5. Look for a pocket watch and gear with good stats and skills.