In the first 30 seconds, your résumé has to (almost literally) grab the reader by the throat, jump on his chest, and scream HIRE ME! (OK, I'm exaggerating for effect, but that's to illustrate the importance of getting the reader's attention.) How to do that is to show the reader right away that you understand the employer's business problem that caused the opening, and that you are THE solution to that problem.
How do you do that? One tactic is by using an objective, such as: "I am seeking a full time position with [name the company you're applying to] as a [name the position you want]. Having succeeded in [your experience #1, as shown in the ad], [your experience #2, as taken from the ad], and [experience #3, as taken from the ad], I am confident that I will provide you immediate value. I will help your company achieve its objectives."
If you use an objective, it must be all about what you will do for the employer, in the same way that your entire résumé has to answer the employer's "What's in it for me?" question. From your first words through your last, that objective must convey the message that "You're looking for A, B and C skills and I do them. And what's more, I do a great job at them."
The truth of it is, your résumé only gets about 15 seconds of that reader's time, if you're lucky. In a perfect world, every résumé would receive the attention it deserves and every deserving jobseeker would... But you get the idea. It's not a perfect world. And in reality, the reader will make a judgment about your résumé by the time s/he's only about a third of the way down.
A better tactic than the objective is to write your Unique Selling Proposition, or USP,in the form of a strongly worded Summary. That Summary, when properly written, should demonstrate why you should be chosen out of the 400 or so applicants who have answered the advertisement. Such a USP might look like this: "Analytical, organized Financial Analyst recognized for achievements in administrating new loan funds, implementation of loan closing, and evaluating borrowers' ability to repay mortgages. Strong problem-solving skills. Analyzed other branches' loans to ensure 95% loan confidence rate."
Now the reader has a clear picture of who this applicant is and what s/he can do for the company. This applicant has made a strong case for him/herself, and what's more, s/he demonstrates how unique s/he is. This summary shows accomplishments, skills, and abilities in a much better way than the objective did, because each statement is a quantifiable. The summary also has an advantage over the objective in that most hiring managers and recruiters prefer a strong summary because objectives tend to be about what the applicant wants, rather than what the applicant has to offer the company.
However, regardless which you use, objective or summary, keep in mind the employer's question: "What's in it for me?"