Be sure you are on a true trusted site. There are many scams.
Some sites force you to use more advanced pdf readers. The PDF they made allow user input to the pages (boxes for personal info) so they can be printed or faxed back. It makes a neat typewritten looking application.
If you don't want to install applications see also portableapps.com. Good free, portable applications. They do not let you just open pdf files, you have to choose the application or open application then open file.
"Best Practices", Event viewer, host file, perfmon, antivirus, anti-spyware, Live CD's, backups, are in my top 10