The mistake
Assuming every 'good day' is good for everyone. A day auspicious in general can still clash your personal animal — the almanac is read against the person, not in the abstract.
What the classics actually say
Twelve day officers rotate in a fixed order — Establish, Remove, Full, Balance, Stable, Hold, Break, Danger, Success, Collect, Open, Close. Each favours a kind of act and warns against its opposite; 'Open' and 'Success' days suit beginnings, 'Break' and 'Danger' days do not.
Getting it right
You read the almanac by matching the day's officer and clashes to your intended activity and your own animal. A day that clashes your animal is one to keep light; a supported officer is a day to push.
Try it yourself: The Chinese Almanac (Tong Shu) is free on FengMaster, computed to the letter.