From hacking reports these seem like the leading reasons to why people get their accounts hacked:
(In no particular order)
1) They have large amounts of runes on their account.
2) They have large amounts of gold on their account. This includes advertising and selling expensive items in the auction house an/or global chat.
3) They **** off someone or some guild
4) Their character(s) generally have valuable gear and purposely shows it off.
5) Buying of accounts or gold from non-gameloft sellers.
6) Falling for scams.
7) Having a password that is insecure and is used for online sites also.
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Solution to 1 and 2:
So I would advise never having more than 50 runes at a time max and no more than 1000 gold. Send all the rest of your gold to a alternative character.
Note: Also, makes sure your baking character isn't on the same account as your main characters. It would be a shame to lose your all of your accounts over a measly sum of gold. I would also advise parking your gold storing account at a less popular auction house such as the one at Crimpson Tower, Antoria or Bellshoal, Tear Coast.
Solution to 3:
Don't **** off people too bad, keep in mind that it is only a game and yelling at someone with blind insults really never got anyone anywhere. This includes in game and in real life. Unless your actually have a rational insult then people really couldn't care less.
You can always block people and turn off specific chat channels.
Solution to 4:
This includes epic trinkets, epic pets, paid pets, and even just large numbers of epic weapons.
Unless you're gearing up for a dungeon run or a pvp duel there really is no reason to show off your epic weapons and gear. I would say that 2 epics is probably a average amount, but if you have 3 epics and 2 epic paid trinkets then that's a bit excessive.
Solution to 5:
Never purchase gold or accounts from non-Gameloft sellers. You may never see your investment again if you purchase from an anonymous seller.
Purchased accounts and issues dealing with purchased gold will not be supported by Gameloft.
Solution to 6:
Just because it's a game doesn't mean that you shouldn't use your common sense. There are people who purposely prey on those who are gullible enough to fall for phony scams. Remeber that Gameloft will never ask for your password. So don't give out your password to anybody.
Another common scam is for a guildee or someone to purchase runes on your account for you, but first you must give them your password.
Solution to 7:
Don't make your password "abc" or "123" or anything easily guessable. Don't associate your password with your Gameloft live email or character's names. Also, most importantly, don't use the same password for online websites as you do for your account.
If your password appears on the list below then I would highly advise you change it:
http://www.whatsmypass.com/the-top-500-worst-passwords-of-all-time
Some people say that changing your password is useless against hackers. Yet in the case that someone does obtain your password at least they don't gain access to bank accounts and other important things of yours.