Tips and tricks for submitting CL ads:
1. Make sure you have a good story such that it's clear that this is a rehoming listing and NOT a breeder ad. Otherwise your listing will be flagged as against their TOS (terms of service) and quickly removed.
2. Pictures help A LOT! Upload pictures to your listing.
3. Incorporate as many keywords in your listing as possible. This helps people find your listing if they are searching for something in particular.
4. Make sure you include an adoption fee for your guinea pig(s). $20 - $25 per guinea pig is good. NEVER say "Free to a good home."