Deep clean apt before moving out

My boyfriend is moving in with me and is leaving his apt he’s been in for 7+ years with another friends. So, we’re talking about 7 years of 2 bachelors who ‘think’ they have good cleaning habits. The collection of dust that’s piled up around the edges/baseboards over that time would imply otherwise lol. It’s not horrible, it’s just never had a full deep clean.

His Mom and I are going to do a deep clean, and basically want to give the landlord as little as possible to deduct from the security deposit.

Looking to collect any tips that people have. Thanks!!