Guest blogging can either enhance your SEO efforts or lead to penalties if done incorrectly. According to Matt Cutts, guest posting is acceptable as long as it is focused on providing quality content.
Guest blogging becomes spammy when:
The content is thin and offers no value.
It is used primarily for link building.
Posts are published on irrelevant or low-quality sites.
To use guest blogging effectively:
Focus on industry-related content.
Target reputable websites with genuine audiences.
Include thoughtful, engaging insights and provide real value.