Leveling Your Character
It can be confusing when you have six different classes all with different levels. How do you know when to level your first class verses your other classes? Do you actually have to stay 5 apart in all your classes? Am I going to break my character if I level on my own terms and not the games? I'm going to try and cover as much of this as possible, and clear up some questions any new players might have regarding a new character.
When To Level Your Second Class
The game does a good job of letting you know when it's time to level classes other than your primary, and Mush-Z makes this even easier. If you press alt+x in game you'll get a message like ' 14.5mill xp / 26 mill xp to level Thief (56%)'. This will always show you the cheapest level, and generally speaking you always want to level your cheapest level next. If you do this your character will stay balanced, the way the game intended your character to be.
Alt+x is the easiest way to see what your next level will be, but sometimes it will say the experience required, but no class to level. It might look something like '14.5mill xp / 26 mill xp to level (56%)'. This means two or more of your classes are tied, and you can choose which one you level next. In this situation I normally just type 'level', and then use a control tab to go to my output window, and I read up from there to go through my classes. You can check what classes are tied, and then when you have the required experience just level that class.
You'll have the first tie in classes around level eight or ten, shortly after starting the game. It will be a five way tie between all the classes which aren't your primary. This is when you get to pick your second class. The next tie will probably come when it is time to pick your third class down the road. Later on ties in micro levels will be quite common, and you can simply just pick which class you think is best to level and level it.
Staying Five Levels Apart In Classes
Not following a strict five levels apart leveling schedule seems to trigger some players for some unknown reason. Granted in the vast majority of situations it is best to follow the game's leveling schedule, but it is not set in stone. For example with my warrior cleric character there was a point where both my first and second classes were tied at level 30. I wouldn't suggest this, but it worked for me at the time with how much I was soloing, and the use of the level 29 and 30 cleric spells.
The easiest way to look at it is. It's normally okay to squish your levels together, but not to spread them too far apart. For example if you are level 30 in your primary class, but don't feel you are ready to go to the mainland yet. It is okay to level your second through sixth classes, but to hold your main at level 30 for a little bit. This is not the best idea, as I found out through first hand experience, but it won't break the game for you.
It is simply important to remember the game is set up how it is for a reason. Being five levels apart really does work out best, and it's how your character naturally levels, but it isn't set in stone. You can push levels around, over level a certain subclass to unlock something, level one class past another to change your character. All of these are okay, and they won't break your character. The best thing is, no matter what happens you can always go back to leveling normally and your character will sort itself back out to being five apart every time.
What Not To Do
For simplicity's sake, don't over level your first class. Yes it isn't guaranteed, but more than likely if you do this you are going to break your character. You aren't going to have the stats to unlock most things, and even if you do you aren't going to have the supporting spells from your subclasses to survive in higher level areas. A higher level primary class does not mean you can magically survive in higher level areas. It can help some, but without subclasses being leveled up as well, and knowing all the important spells and skills you are going to have a very rough time of it. You'll also be reducing the areas you can run for decent XP, and it will be harder to level up your other classes because of it.
Over level the lower classes, but don't get impatient and push your first class up to 39 while you are still total 135. You're going to get yourself backed in to a corner, and it is going to be a lot of unnecessary work to fix your character. One level here or there to give your primary is always fine, we all do it, but when you have 10 levels between your first and second class, you've messed everything up
Leveling One Class Past Another
This is more common than you might first think, especially for new players. Before there was an amazing new player class and subclass guide on BSG, new players never knew what classes worked best where. The only way to fix this was to push one class past another to reform your character how you wanted it. I was originally a sixth class necro on one character, but I leveled it past my fifth class and became a sixth class druid instead.
The process for doing it is quite simple, just ignore the suggested level from the game and only level the class you want to bump up in your subclass order. It takes a hell of a lot of work. If you want to push a class past another I would suggest doing it before you are 30 in your first class. This reduces the work involved, but either way it is going to take quite a bit of XP to get it bumped over the next in line. Once you start you'll realize how much the xp for the class jumps, and that is because you'd normally be leveling that class with a much higher xp cap. Like everything involving leveling, it is doable, but it may involve some work. If you wait until you are a high level then it is going to be even more work, and a complete nightmare. It is manageable if you do it before primary level 30 though, as long as you are stubborn enough to grind it out.
Conclusion
There isn't much to worry about, no matter how messed up you can make your character, it is always fixable by leveling normally. In good news, if you just follow the game's leveling schedule you'll never have anything to worry about. Even if you push a class up one or two levels out of line you'll still never have anything to worry about. Just try not to push your first class too far ahead, and you'll never have a leveling issue.