PCR with very low DNA concentrations

[Lord Antarchon]

Is there a established strategy one follows when trying to get PCR
product from low concentration DNA, i.e., you increase DNA concentration
first, then primers, etc. I am trying to amplify a low-expression gene
from a lambda gt11-based cDNA library.  If anyone has a clue, please
email mdc128 at psuvm.psu.edu, because I'm starting to get a bit vexed with
my reactions.