In 2011 I suggested asking websites that linked to you to add a title attribute containing keywords. That attribute may appear when someone hovers over a link with a mouse. I hoped it would add SEO value too. It is not a sound main strategy for links.
Google mainly recommends clear, visible link text. A title attribute can sometimes serve as a fallback when a link has no text at all, but that missing text is the problem to fix. A link reading “read the study on local searches” tells visitors more than “click here” with hidden keywords attached.
Write for the person using the link
Visible text should give a fair idea of the destination. Name the subject or action without making the link needlessly long. The same principle applies to outside and inside links. Readers should understand why they are leaving a site and what they are likely to find. This also helps people who scan links apart from the surrounding paragraph.
The W3C warns of support limitations for title attributes. Essential information belongs in the visible text or directly beside it, not only in a tooltip that some devices never show.
What should you ask another website?
If a partner links to your article, thank them and check that the URL reaches the right page. If the link text is unclear or the article name is wrong, politely ask for a correction. The aim is a reference that makes sense to their readers. I would no longer send a list of required keywords for a hidden attribute.
My old tip came from wanting to get more value from an earned link. A better route is simpler: make the reference relevant, accurate and understandable.