How do I use old websites to best effect?

[benacuity]

I own a couple of old sites with DA of 15 and 17 which don't really rank for anything, as well as my main site which as DA of 29. Can I forward these domains to my main site to increase the DA of my main site. Alternatively is there any other way of making use of these sites?

[Eblan]

301 redirects will pass some of that sweet link juice from your old site to your new one.

Check this out!

Hope it helps!

[TakeshiYoung]

301 redirects can pass some link value, but some of the link value will get lost.  Also, unless the old sites are topically similar to the new site, Google may not pass any link value at all.

If the sites are related to your new site, try including a couple of links from your old sites to the new one.  Write some new content for your old sites that's topically related to your new site, and include some in-context links.