D&D 3.x Determining CR (3.5)

[Grumbles]

Hello everyone,

I'm fairly new to the DM chair, and I'm experiencing a few issues... I'm currently being troubled by what CR the NPCs I'm creating should be. The main issue is coming from NPCs that have class levels (i.e. a 5th level human cleric or a 4th lv bugbear fighter).

Basically... When adding base class levels to a pre-existing monster/creature template, how is the CR of the creature changed?
If anyone could help with this, that would be great.

 

[anest1s]

Everything about that is here Improving Monsters :: d20srd.org (for 3.5) or you mean something else?

 

[Grumbles]

Perfect, thank you!