When evaluating Full Spiral Saving Bulbs (CFLs), you must prioritize Luminous Efficacy, which should ideally be above 60-70 lm/W to ensure genuine energy savings. Check the Color Rendering Index (CRI); a value of Ra ≥ 80 is standard for indoor use to ensure natural color representation. Additionally, verify the Average Rated Life, which should range between 8,000 to 15,000 hours. For the spiral design, ensure the tube diameter (e.g., T2, T3, or T4) matches your fixture requirements, as thinner tubes often allow for more compact designs with higher efficiency.