Manual Link Exchange could be 1 0n 1 (reciprocal link exchange) or 3 way link exchange,
There are many article you could find in google reguarding this kind of link exchanges,
I personally prefer 3 ways link exchange, I think it has got more weightage than normal reciprocal link exchange,
What is 3 way link exchange ?
Link exchange should be in related niche websites for SERP, In 3 way link exchange website (A) points a link to website (B), In return website (C) points a link to website (A). [Website (B) may or may not have a link pointing to website (C)],
This is a nice way to create backlinks from related niche websites,
Many webmaster are using this technique to promote their websites.
TIP: If you are a webmaster then keep an habbit of checking bottom link exchanges and traffic trade links on every website you browse , you will definately find something that i may not know .