Hey welcome to the game. I will hopefully answer some of your questions and if u have anymore will be happy to help.
Now usually when ppl post there levels they will do it the **/## fashion. You may notice in my sig below I have a bunch like this. The first number represets your BASE level, this is the overall level of your character. The second number represents their JOB level. Your Job level is what gives you the "moves" for your class. For example in order for mages to learn magic they need to put points from JOB levels into spells. Likewise Thiefs need to put points into there skills as well.
Now when you start out as a Novice you have MANY different paths to choose from. I am not going to explain them all but will explain more about the Thief as this seems to be what your interested in.
When you get to JOB level 10 as a Novice you can change your job to any of the First Classes like Thiefs, Mage, Swordsman etc... Normally you will be around level 12/10 Novice when you finish the training grounds. Then when you become a Thief you will be at 12/1 because you have just started a new "Job".
You will continue to Level your Thief and when his JOB level gets to lvl 40-50 (50 is max job a thief can get), you will have the choice to change into one of 2 Second Classes.
The Thiefs second classes are Assassin or Rogue. FYI Assassin is to long to type most of the time so people will shorten it to Sin. Likewise Assassin Crosses (will explain more about this later) are referred to as SinX's.
Now I said you can change at job level 40 as a Thief to either of these, however you see when you change your job you will have to do certain "tests" or "Quests" so that the various jobs accept you. These are usually not to hard but if you do goto Job level 50 before doing them you usually get better Rewards and can also skip certain parts of the test because of your life experience.
Ounce you change to your Second class of either Sin or Rogue you will then keep leveling. You hit your Max level as a 2nd class at level 99/50. So in your case you would lvl your Sin upto level Base lvl 99 and Job lvl 50.
At this point you have 2 choices, you can either go for your 3rd class right away and become a GX (Guillotine Cross being to long to type) but this is a
BAD IDEA The best thing todo at this point is whats known as "Transcending" or "Rebirthing" they mean the same thing.
What this does is resets your character to a level 1/1 "High Novice" which has MORE stat points then you did the first time as well as other benefits like 25% more base HP/SP.
Ounce you got to job level 10 you would change into a "High Thief" and would again level to job 40-50.
At this point you would go back to where you "Rebirthed" and become a "High Assassin" better known as Assassin Cross. FYI the "High" 2nd classes usually get different names, the only exceptions really being "High Wizards" and "High Priests".
The Reasons you want to be a HIGH 2nd class are that first is the higher HP/SP but also High 2nd classes can reach a Job level of 70 instead of the 50 from before. They also get some GREAT new moves. Rebirthing is really a MUST, anyone who tells you not to really just wants to be able to kill you easier and in no way should be trusted.
SinX's say hello to SOUL DESTROYER (which u can just tell is super cool) and Enchant Deadly Poison as well as a few others.
Think that answers your questions for now.
EDIT: I also have a Thief Leveling guide with links pinned in this section as well.
http://forums.warppo...topic=28579&st=Feel free to PM me if you have any specific questions as well. I like to do things like answer questions at work, helps make the time go by faster.
Edited by EvilLoynis, 01 September 2011 - 06:30 AM.
http://forums.warppo...x-newbie-guide/ this was the guide i was reading. what do assassin cross, guillotine croos, GX mean and how do you actually become an assassin, i mean is it sth like novice-thief-assassin. and what does for example 90/22 mean? Is it sth like a level? And on the website the info says that the thief becomes either a raider or a scout. Would really like to start a thief but these guide give me more questions than answers 
