Trying to avoid a rookie mistake

This is directed to Steve or Missy or anyone else who could answer a few simple questions regarding computers and internet communications. I have been sort of stumbling thru cyberspace on a trial and error bassis. Missy knows this because she has bailed me out before on a rookie mistake. Anyway I learn a little each time and move on. As time has gone on I now feel like I have created a situation where I need some security guidelines for myself to protect the information and assets I have out there. Missy helped me with reccomending virus protection software I have in place. But that won't protect me from myself making some stupid mistake. 1. Opening files that have a warning about the security certificate of the source seems like a stupid thing to do but I have done it. 2. I don't know what a cookie is but it sounds like a good way to open yourself up to problems so I havn't done it. 3. I recently heard someone say never open your bank act or other secure information sites from yahoo. I do it all the time. I hope I,m not breeching any Blog rules by talking shop to you computer pros but I thought I could get some good advice witout having to work to hard for it. And you can ask me about the best way to remove and replace that rotting floor joist or rafter any time. Missy willhave to come up with something else since she has that base covered. Maybe some surefire methods for beaver relocation