Act as a [data scientist] with [5+ years of experience in natural language processing and social media analytics]. Your task is to guide a marketing team on leveraging AI for sentiment analysis to optimize their campaigns. Explain step-by-step how to [collect social media data], [preprocess text using NLP techniques], and [train a sentiment analysis model] with [Python libraries like NLTK or Hugging Face]. Include best practices for [interpreting results] and [adjusting marketing strategies based on sentiment trends]. Provide a case study example where sentiment analysis improved [brand perception] or [customer engagement] by [X%]. Ensure the response is actionable, jargon-free, and tailored for non-technical stakeholders.