relevant skill modifier or other appropriate modifier to your check against the target’s DC. [...] the counteract check modifier is your spellcasting ability modifier plus your spellcasting proficiency bonus, plus any bonuses and penalties that specifically apply to counteract checks.
the results are based both on your success with the dice and the level of the ability/spell used when performing the Counteract
Critical Success Counteract the target if its counteract level is no more than 3 levels higher than your effect’s counteract level.
Success Counteract the target if its counteract level is no more than 1 level higher than your effect’s counteract level.
Failure Counteract the target if its counteract level is lower than your effect’s counteract level.
Critical Failure You fail to counteract the target.
This means that, against level-appropriate effects, you are spending one of your higher spell slots (or similarly powerful resources) for the attempt to overcome a negative effect, requiring you to roll in the range of 8-12 to get a Success. That means, without modification, you can expect to fail at least 1/3 to 1/2 the time. Against some effects that this would represent a quality of life increase, this is fine... but when attempting to overcome permanent Blindness or Mummy Rot (for instance) you may not have the luxury of accepting failure.
When out of combat, what methods are available to boost your Counteract checks, particularly for spells?