Though it would certainly be fun to take all the credit for saving the world, most heroes find that allies add a little interest to the RPG.
First of all, there must be a female ally. She is particularly important, as her presence protects you from feminist attacks. She allows for various romantic entanglements to form, and that tension creates a number of Overly Emotional And Mushy Scenes that allows the hero/ine to have a few good laughs.
An important function of the female ally is to draw in male audiences. Thus, the hero/ine must be sure, when choosing a female ally, that she is a comely young lass. She should have a tendency to wear Shrunken Outfits, and be either a quiet and dignified magician who can be knocked out with a stick, or a rowdy and agile warrior who has no defense power to speak of. These weaknesses are very necessary, because no one must be allowed to steal the spotlight from the hero/ine.
While the female ally takes care of male audiences, a male ally has to capture the hearts of the female audiences. This being said, the hero/ine should choose an ally from among the winners of the Mr. Long-Haired Male Who Looks Like a Female Contest. This ally should have some dashing hair colour such as black, silver, or brilliant yellow. If necessary, a bottle of hair dye can and should be used.
Though he can create some amusing tension when paired with a female ally, you will find that this dashing ally tends to remain single and be too serious to waste time courting girls. This holier-than-thou ally, when coupled with a Tragic Background, will give rise to numerous instant shrines and raise the popularity of the RPG (and hence the hero/ine) tenfold.
Finally, one of the allies should be a powerful, yet stupid fighter. This ally can be male or female, though a physically-unappealling male is usually the case, since females should be restricted to the two types listed above (to avoid confusing the audience) and it is not good for the popularity of the RPG if a good-looking male is also stupid.
Now, this ally is perhaps the most important one in terms of actual adventuring. The hero/ine may deal a few blows to a monster for the sake of appearances, but this ally will do the actual dirty work of digging into the creature's guts. After all, the hero/ine can't actually be expected to get all bloodied -- s/he still has to look good so villagers will give information rather than run away screaming from the sight of blood.
Since the hero/ine will be taking all the credit for his monster-butchering, this ally must have a low intelligence to keep him from starting a mutiny. Finally, this ally can be counted on to provide some comic relief, though mushy moments involving the female ally should still be the main source of humour.
Various other allies can be collected to lessen the workload of the hero/ine, but most should fall into the general categories listed above. Sometimes an ally will fall into a fourth category, that of pure mediocrity. This ally is mainly used for comic relief, or as an excuse to embark on a mini-quest.
It is usually the case that a strangely high percentage of the allies have some painful history, or act like they're suffering from Prozac withdrawal. This is normal. Most people with healthy lives, a loving family and steady jobs do not know how to handle death-causing devices nor do they run around risking their lives when they have nothing to avenge/discover from their past. Rather than spending a large portion of your RPG time looking for a good psychologist or counsellor, you should let these people work out their problems themselves. This will lead to various subplots and Cheesy Moments that stretch out the RPG (aka give the hero/ine more time in the limelight) and provide the villain with enough time to prepare for a truly devastating final battle.
The hero/ine should not fear that s/he will not get along with the rest of the party. Since the hero/ine is a key part of the RPG, they will suck up to the hero/ine just to keep their roles. Thus, they will all inexplicably develop great friendships and find the meaning of their existences during their stay with the hero/ine.