You can choose to have 2 different kinds of professions in WoW. There are primary and secondary professions to choose from. You can choose to have only two main (primary) professions but can have all the secondary professions if you want to.
Obviously with the ability to take advantage of two primary professions and an unlimited number of secondary professions it is wise to do some research before you choose your professions. Many new players find that they waste a lot of time levelling up their skill points just to discover they have chosen the wrong professions.
Because professions go to 450 level it is a great waste of your time to level up a profession that you cannot use properly. This is made worse because you have to start again from scratch if you change professions. Choosing your primary and secondary professions based on your class and the style of play you have is the fastest way to help level up your character and power up your avatar to levels that will astound your guild members!
There are also certain things that you can do to ensure you level up your profession skills quicker than normal and I will mention this at the end of this article.
However, at the start you should just make sure you have picked the right professions. This is the most important part of levelling up your character as far as the professions are concerned. Many new players give little or no thought to which profession they choose and therefore usually end up with professions that are useless to them.
Tailoring would be pretty useless to the warrior class for example. Blacksmithing would prove much more useful to a warrior as it would allow the warrior to forge new and improved weapons and armour.
The tailoring profession would be much better suited to a character that belongs to one of the classes that use cloth armour.
Once you know which professions best suit your class it is just a matter of matching up primary professions and secondary professions that complement each other. As an example mining and blacksmithing are 2 primary professions that work well together.