I have very old and huge site with milions links and big traffic. I haven't made any backlinks for a year. What would be safier, more effective and better to get higher rankings for medium and hard keywords: make more good quality tier1 backlinks or make tier2(some pages have tens of old high quality backlinks)? What would you recommend for tier2 if money site safety is the most important(what kind of links)? Any services from marketplace?