Get an introduction to the target company through a referral if possible.  A lot of the companies that retain us even talk explicitly about no agency referrals on their website.  There are times that going in through HR or their staffing org can be to your benefit but more often that not it helps to have a referral with a VP in their title to get you that introduction.  You might still be a long way from getting a fee agreement signed (retained or contingent) but you'll be a lot close than being one of the hundreds of agency recruiters leaving voicemails for the VP HR or Staffing Manager.