How can you identify a valuable Spider-Man comic cover from the classic era (1960s-1970s)?

Identifying a valuable classic Spider-Man comic cover involves several factors. Key first appearances (characters, storylines) are paramount. Condition is critical, with higher grades fetching significantly more. Rarity (lower print runs, variants) also increases value. Professional grading by companies like CGC or CBCS provides authentication and a standardized condition assessment.