In general, it is easier to work with ranges than with selections (and,
since ranges does not depend on the selection, there is no need to deselect,
either). For example, the following code:

If ActiveDocument.Content.Font.Name = "Tahoma" Then
  ActiveDocument.Content.Font.Size = 15
End If

would change the font size of all text (in the body of the document) to 15pt
if the font name of that text is Tahoma.

But note that since you can specify the font on the character level, the IF
statement does not necessarily evaluate to TRUE.

Hi FotoArt,

the easy thing at first.
selection.collapse

Then, there can be several issues.

If there are different fonts in the selection,
the condition would never be true.
To check it, try it with different fonts in the selection:

MsgBox Selection.Font.Name = "Arial"

Understandably, for sure.

But then, even if you have formatted
all of the doc in "Arial" and the doc is not quite small,
the condition would never be true.

I think I've read about that once,
but can't remember exactly.

However, for 11 pages of "The quick brwon fox",
the following code stops after character 21119!

Also
activedocument.range.font.name = "Arial"
returns false!

So you got to process smaller portions,
besides the first mentioned issue.

And google here for range vs. selection,
it's worth finding out the difference.

To the best of my knowledge.