I am no VBA pro but I do write several semi complicated macro.

Here is that I wrote to check for two errors using if then else
statements. It works perfectly but I wonder I it could be written more
professionally.

If error1 < 0 Then 'error 1 check
If error2 < 0 Then 'error 1 & 2 found
MsgBox error1 & " data input are missing and highlighted in
yellow. " _
& error2 & " entries are a missmatch and highlighted in blue."
Exit Sub
Else 'error 1 only found
MsgBox error1 & " data input are missing and highlighted in
yellow."
Exit Sub
End If
Else
If error2 < 0 Then 'error 2 only found
MsgBox error2 & " entries entries are a missmatch and
highlighted in blue."
Exit Sub
Else ' no error
Exit Sub
End If
End If