Assassins are not the best at hunting monsters, but exceptional when it comes to one-on-one with players. Assassins can double as spies or thieves, or any other sort of unsavory character who relies on wit or deception to survive.
Hiding, stealth, poisoning, backstab, critical strike, and a 90+ combat skill is a must. Skills like Examination, Common Lore, Snooping, Stealing aren’t vital. Search is for spotting thieves. Tracking is for hunting down targets. Traps are a very easy way to plan ahead and lure someone into an easy death.
Dual Identity. If you want to get away with criminal acts, you’ll need another name. There are disguises in game, but a dual identity is a much more powerful version of this. It costs 1 XP, so you’ll have to have RPed on Dark Age II before you make take dual identity, or you’ll have to apply with an exceptional application that explains why you have a dual identity.
Make Your Own Poison: It’s a huge drain, but take alchemy if you feel you wont have a supplier for poison. It makes getting a hold of poison incredibly easier, but also will probably put you in negative points. Suggested alchemy: 70. (If you go negative, you could set snooping and stealing to 0)
Treasure Hunter?: You’re just 90 cartography away from being able to pop open chests. If you want to hunt treasures, don’t pass up the chance.
Better Hunter?: If you’re worried you wont be able to take on groups of monsters well, think of dropping snooping and stealing for Leadership. It’s a great skill. Snooping and stealing are great ways to make money, but not necessary if you’re willing to hunt for gold.
At this point, you really should have an idea about what your character is going to be. Backgrounds are something very personal that shouldn’t be described in a guide. They should fit your character, not an ultimate build. Give yourself flaws, give yourself talents. Backgrounds are something you should roleplay, not just take.