CRISPR KO in mammalian cells: optimizing sgRNA design, delivery, and validation

[OliverA]

I'm a molecular biology researcher, and our lab is planning our first experiments using CRISPR-Cas9 to create a specific knockout in a mammalian cell line. While I understand the theory, I'm concerned about practical issues like off-target effects and ensuring high editing efficiency from the start. For researchers with hands-on experience, what were the most critical optimization steps in your sgRNA design and delivery protocol, and which validation methods did you find most reliable for confirming both on-target edits and assessing off-target activity in your initial experiments?