Lots of research.

Goof reply Rick will help us all, will read. Thanks

Hi. Not sure if you've seen this. Writing Product Reviews of Stuff You Don't Own

I agree with the other comments, research and research. Even if you are using a product yourself, you have to research what other users are experiencing with that product to get to know all the ins and outs for that product.

Success.

Yeah… just research & cross referencing
And if you get a good enough feel for the
product after that, I think your at least entitled
to give an opinion or provide a review.

The key is in how things are worded..The Terminology you choose
and if your maintaining your integrity & not mere just plucking
things out of the clouds or sensationalising things…then you should be ok.

Everyone learns & makes mistakes…and if you do, but you know it was a genuine mistake, or you weren't privid to that info at the time

Then as long as you know…. then you'll be ok..

But yes… Research as much as possible first..
And if someone makes a claim about a product
then Ref: Them always, if you have no real proof of that claim.

Bless R

Lots of research and reading about it.

If you have a Mac I HIGHLY recommend ScreenFlow, otherwise there's Camtasia

I use camtasia but there is also a free and paid version of Jing.

I've used one called CamStudio, which I found easy to use. I did a quick search to see what else might be out there, and found this (which you might be interested in):
http://elearningindustry.com/top-10-free-camtasia-studio-alternatives