What, Where & When
Make note of the types of pests that were present, what times they were present and the population levels they reached throughout the growing season. Keeping this information year after year will help you improve crop success because you can prepare for expected pests and diseases instead of being blind-sided once the pests or damage symptoms appear. Using a Garden Journal is helpful in documenting timing of issues, their treatments, planting cycles, weather anomalies, etc.
Look over the information you have logged throughout the growing season and Evaluate what was helpful and what may not have been. Make decisions looking forward to the next planting season to help avoid unnecessary issues in the future.