For related pages that don't really work into the text, use a "See also" at the bottom of the appropriate section of the page:
''See also: Disabled travellers, Yosemite National Park''
If the page isn't broken into sections, simply put the "See also:" at the bottom of the page itself. "See also:" should be the last thing on the page.
You can also add the related template to the bottom of the page <nowiki>{{related|examplepage}} </nowiki> which will show the link in a "related pages" block in the navigation bar on the left.
Do not link to articles in other namespaces (Wikitravel:, User:, Talk:) from the main namespace. It's totally OK to link from those namespaces to each other or '''to''' the main namespace, but not vice versa. An exception is for editorial or procedural text like Article status messages ("Stub", "Outline", etc.) In these cases, the links should be hidden inside templates.