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I suggest to search for such blogs manually and not submit to any blog networks - that way you keep your risk of getting caught in spam lower. Write a personal email to them if you find a potential blog and write them a custom offer, that works best. and it doesn't have to be only guestblogging. Also, get your business partners etc. to link to you. What you need is some nice variation and not all links coming from the same type of website.