The trick is that I name each label with the same prefix. In the case of this blog, I use
tag:. Once each label has a prefix, I can use Google to search for articles with any set of labels. For example, if I wanted to search for all posts tagged with
Tip, I would enter the following terms into a Google search:
"tag iPhone" "tag Tip". Had there not been a prefix, my query would have needed to be
iPhone Tip, which would find many articles that only mention any of these words and aren't necessarily tagged with them. In fact, in the case of my blog, I have both words listed on the right side of each page, meaning that every single one of my posts would show up in the search results.
/search/label/tag:MyLabel). Unfortunately, this means that the list needs to be updated every time I create a new label.
The final tip I'll leave you with is that when you create a link to the Google search, I would recommend adding
inurl:html. The first part is obvious: it makes sure the results are on your own website. The second part ensures that the results will only include actual articles rather than pages which show snippets of articles (e.g. the home page or label search page).
You can see how all of this works by clicking on this link which will show you all my posts that are tagged with