When purchasing wigs, you should consider the following factors:

1. Clarify Your Needs: Determine the purpose of buying wigs, whether it's to cover white hair, adjust the hairline, or pursue a fashionable hairstyle.

2. Choose the Right Material: Wigs are mainly made of human hair and synthetic fibers. Human hair wigs are more realistic and can be dyed and permed again, but they are more expensive; synthetic wigs are relatively cheaper but have lower realism and texture.

3. Consider the Workmanship: Wigs can be categorized by workmanship into full hand-tied, half hand-tied, and machine-made. Full hand-tied wigs are lightweight, breathable, and more realistic; half hand-tied and machine-made wigs have relatively poorer breathability and realism.

4. Size and Color: Choose wigs that matches your head shape and hair color. The size should be slightly larger than your head circumference to ensure it doesn't slip off when worn, and the color should coordinate with your skin tone and hair color.

5. Breathability and Comfort: Opt for wigs with good breathability to reduce damage to the scalp, and ensure the wig is light, soft, and comfortable to wear for extended periods.

6. Naturalness and Realism: The wig should look natural and fit seamlessly with your own hair, with consistent length and color.

7. Durability: Consider the wig's durability; high-quality wigs are more durable, less prone to deformation, and can be used for a longer time.

8. Return and Exchange Policy: Understand the merchant's return and exchange policy to support returns or exchanges when needed.

9. Maintenance and Care: Choose wigs that is easy to clean and maintain to extend its lifespan and keep it looking good.

10. Avoid Inferior Wigs: Do not buy inferior wigs made with low-quality materials to avoid allergies or damage.

11. Suitable Style: Choose wigs style that matches your face shape and style to ensure naturalness.

12. Certification and Merchant Reputation: Ensure you purchase wigs from reputable and reliable merchants, and opt for products with relevant quality certifications.

Considering these factors can help you select a high-quality wig that suits you and effectively avoid unnecessary trouble and losses.