Sending a generic resume is a mistake.
The lack of targeting – aligning your skill set with the job requirements – puts you at a big disadvantage. Hiring managers can smell a standard, one-size-fits-all resume from a mile away.
Some basic tips to help:
1) Start with a "core" resume that is easily tweaked and targetable.
2) Use the job requisition as your guide. What is the company looking for? What does the position require? How can you bring those things to the forefront in your resume?
3) Do not underestimate the power of automated resume screening software. Are you using terms that represent your abilities and match up with what you are seeing in the requisition?