Here are some quick hints & tips which you can use to better your Lineage 2 gameplay:
Interface:
If your character appears to "fall through the world", this can be corrected by restarting to the character selection screen and logging back in.
Using ALT+TAB while in the game may cause problems, do not use it.
Trade:
Always check the color of private store messages. Purple means 'Selling', yellow means 'Buying'.
Do not drop an item unless you are willing to risk losing it forever.
You can't drop items on the ground.
Items:
If you have three swords, one of which is enchanted, the blacksmith will randomly combine any two of them when making dual swords.
You can claim freight from every town.
Pets:
Is no need to double-click on pet food, you only need to put it on his inventory.
The food will be automatically consumed when the hunger drops below 55%.
PvP:
If you are killed by your opponent outside the PvP arena after fleeing from a duel, normal death rules will apply.
Many special attack skills do not work on clan members, party members or white players.
Quests:
Players can have up to fifteen quests at once.
Most quests are repeatable though some are not.
Skills:
Creatures you have summoned with crystals will disappear when you die or log out.
Although Fake Death can sometimes deter monsters, players can still hit you.
Clans:
If a member is dismissed from a clan, the player must wait 1 day(not 5) before joining a new clan and also the clan must wait 1 day before accepting new members.
If a member leaves the clan, only he will have the 1 day penalty, the clan can accept new members right away.


