One of those is this valuable piece by Lincoln Spector here about how to avoid problems when downloading free applications. It's very easy to follow, if that's a concern, and includes quite a few graphics to illustrate points and suggestions he makes.
Two stand out. One is that on websites that have free downloads, there's often a big green button that says "Download Here" (he provides a screen shot...) -- but you shouldn't click that, since those sort of things are actually ad buttons. Instead, there will usually be a separate link on the webpage for a direct download.
Another helpful discussion comes at the end, when he writes (and again, includes a graphic image) --
"During the installation process, keep a sharp eye out for any suspicious options. Installation options such as Express, Default, or Typical installation could mask the addition of unasked-for apps. Always select an Advanced or Custom install option, if offered. For example, iLivid’s default installation setting automatically installs other, possibly unwanted, apps — as shown in Figure 4. You must use Custom installation to uncheck the extra apps."
(While I agree that this is very good advice -- unfortunately, sometimes choosing the Custom installation option can be too bewildering for some people. But happily, not always. That's because choosing Custom is often just as easy as Default or Typical because it will display to the main options you'd want anyway, and it's simply up to you if you want to change that. And know, too, that you can always select the Custom option and if it confuses you, just click "Cancel" to go back to the previous screen and go with Default or Typical.)
Mr. Lincoln notes one other important, comforting thing about all this, if you're downloading standard, mainstream applications: "If an unwanted app gets through and installs itself, it typically won’t be a disaster. A mainstream application such as Chrome will have an uninstaller. Some browser toolbar add-ons can be more difficult to remove, but a quick Web search will in most cases provide a relatively easy solution."