Basic Features
If a feature doesn't have any options or give any powers, instead just giving some persistent passive benefit, use this format. Start with a sentence of flavor text, then launch into "Starting at first level..." for the mechanics.
Features with Options
Some features are going to give multiple options for different builds. As before start with a sentence of flavor text, but then for the second sentence say "Select X, Y, or Z at first level".
Optioned Feature
As per a normal feature, start with a sentence of flavor text. Then, jump right into the details of the option. Close by explicitly highlighting what secondary stat the build uses.
Subcomponents: Some options are structured in parallel with multiple components for easy cross-comparison. In that case there may be bolded text with the colon also bolded to delineate that aspect of the optioned feature.
Features with Powers
Some features are going to give a power. Start with the usual flavor text, then transition with "Starting at first level..." to describe any persistent effects. Finally say "You gain the *feature power* power."
Power for Feature
Same as normal, but replace the spell/exploit/prayer/etc. with "{Class} Feature"
Features with Options and Powers
Some features are going to provide options with powers associated with those options. In that case, follow the formatting for Features with Options
Optioned Feature
Powered Option
Same as Power for Feature