My Recipe Against Dependency Hell

Do you specify exact versions of your dependencies? I mean, when your software package depends on another one, do you write down, in your pom.xml, Gruntfile, Gemfile, or what have you, its version as 1.13.5 or just 1.+? I always thought that it was better to use exact version numbers, to avoid the so called dependency hell, and I was not alone. However, very soon I realized that dynamic versions, like 1.+, give more flexibility. Just a few weeks ago I realized that neither approach is right a...