In fantasy RPGs like D&D or the various OSR clones, a character tends to grow in depth in their particular skills: Wizards learn more spells, warriors get better at striking foes dead, thieves* get better at thieving, and so on.
In D&D, there can be some growth in the breadth of skill. When Fighters reach name level (usually Level 9), they can become Paladins, gaining some clerical skills. Thieves* learn to cast spells from Magic User scrolls. In S&W Complete, Rangers gain clerical and magical user spells.
Generally, I tend to describe the OSR games as games where your character skills grow in depth. Games like Dungeon World, which uses the same classes as D&D, the character grows more in breadth than depth. The Fighter can learn to intimidate someone using his Strength rather than his Charisma stat, for example. There’s always an option to learn a skill from another class, such as the Ranger’s Volley skill or a thief* skill. There is the option to increase offensive damage using the Merciless skill, but generally when you add to skills in DW, you increase in breadth.
So why am I mentioning this subject? How your character develops can be important in the style of game your group wants to play. For a zero-to-hero style of game, where you play a little every week and slowly build your character up, a depth oriented style might be more suitable. For heroic level play or one-shots, a breadth based development might be more suitable. You may not care in detail how well a character can pick pockets, but rather whether he or she is good at it.
If I had a group that could meet weekly, I would be more inclined to the depth oriented approach as we could observe the characters growing in their niche powers over time. But, as I play so infrequently, I presently prefer to develop characters in terms of breadth. The Fighter can fight better than the rest, the thief can do stealthy things better than the rest, and so on. Maybe the fighter can learn to sneak if he takes off his heavy armor and learns from the thief. Maybe the wizard learns some proficiency at arms. Maybe the cleric learns some more worldly skills from the ranger and learns to identify all kinds of animal tracks. Maybe the thief (under some oath not to steal from the righteous) learns some of the powers of a clerical order.
I’m trying to think of some poetic conclusion to this little essay, but I’m at a loss for words. Experiment with your game. See what you and the other players are looking for and go for it.
* I mention thieves over and over in this post, and I must say, I don’t like a thief class. But the thief class is the poster child for character “skills.” It’s so cliche (and not in a bad way, mind you) that some OSR clones (such as LOFP) call the thief a “Specialist” rather than thief.