Hi.
There is the charms I believe are more useful for each vocation:
| Knight | Paladin | Sorcerer | Druid |
1. | Wound | Wound | Freeze | Freeze |
2. | Parry | Parry | Zap | Zap |
As Free Account Knights and Paladin I would recommend using Wound because in free areas I think that all monsters are weak or neutral to physical damage so this rune will be really useful. Considering that with a free account it is not possible to use magic, if not only melee attacks, or the paladins at a distance but without magic.
For Mages and Druid I would recommend both runes mentioned are good. Thinking on the prices of each, I would recommend to buy Freeze first because is cheapest and the mostly monsters available in free areas can be damaged with it (excepts water elementals). Unlike the EK's, the mages can attack in the distance and also can help themselves using runes. I could recommend some defense or protection rune but in my opinion the monsters available in free areas do not have much life and are practically weak to all damages which makes them easy of kill. So its better to use Offensive charms as I mentioned before.
Hope this help you.