I've written a fair number of games that have RPG-like "levelling up," where the player gains experience for killing monsters/enemies, and eventually, reaches a new level, where their stats increase.

How do you find a balance between player growth, monster strength, and difficulty? The extreme ends of this spectrum are:

• Player levels up really fast and blows away monsters without much effort
• Monsters are incredibly strong and even at low levels, are very difficult to beat

I've also tried a strange situation of making enemies relative to players, i.e. an enemy will always be at 50% or 100% or 150% of player stats (thus requiring the player to use other techniques instead of brute strength to succeeed).

But where's the balance, and how do you find it?

Edit: For example, I am expecting to hear things like:

• Balance high instead of balance low (200 HP and 20 str is easier to balance than 20 HP and 2 str)
• Look at easiest vs. hardest monsters, and see what you have in terms of a range