Predicting Signal peptides/leader sequences

[Hinayana Bawagan]

     I have to express viral structural glycoproteins (membrane-bound).  I have several papers of von Heijne, who is one of the authority on signal peptides/
leader sequences.  Question: Is it enough to just inspect the sequence coding
for  my proteins and apply von Heijne's rules or is there a computer program 
that will take the sequence and analyze it?
     Any feedback is appreciated.