The No. 1 tip for landing a job offer in today's tough job market, says HR expert of 20 years

Today's job market seems to be taking a turn for the better, but it's still not as strong for candidates as it has been in recent years.

That can make it hard to negotiate a job offer once you finally land one.

But it's not impossible, says Tessa White, a career coach with 20 years of HR experience and founder of The Job Doctor.

Negotiating a job offer successfully comes down to one thing, she says: Job-seekers "better be crystal clear on their value proposition."

It's the first thing she helps clients figure out when revamping their resume and preparing for interviews.

The mistake people make when pitching themselves as a new hire

A big mistake people make is thinking their value proposition lies in the tasks they've done before and can continue doing in a new job. But this can limit your value proposition and later negotiations because "your leverage is in your outcomes," White says.

"When somebody goes in to get a job and they say, 'I've done this before and I'm really good at it,' that doesn't mean anything. That's just white noise," White says. Consider instead that "the language of business is numbers."

Highlight your value proposition by explaining the main problem you solved in your previous role, how you did it, and what the outcome was, backed by numbers.

For example, say you're up for a job where your main objective is to introduce the company into a new market. Pull up the numbers that support how you've accomplished this before, White says: "In my last job, I did this, and I was able to gain 12% penetration in this particular target market with a 98% retention rate of customers."

"All of a sudden, I want that [candidate]," she says.

Focusing on outcomes can help you 'negotiate much higher pay'

White gives another example of the difference between discussing your previous tasks versus how those responsibilities helped solve a bigger problem: "If I'm applying for a job and I go and say, 'I've done HR for 20 years, and I know how to do business succession planning and recruiting and training' — everybody on their resumes has that experience," she says.

"But if I go in and I say, 'I'm the person that you hire if you're a company that wants to go fast and go public, and you need to build up your departments and make sure they can scale quickly' — I'm all of a sudden the top candidate for the job, instead of just another person who has 20 years [of experience]."

Put another way, "give me your professional highlights reel, not your job description," White says.

"If you're clear on your value proposition," she says, "and you can clearly articulate what the company gets if they hire you, and the problems you can solve and the skills you have to solve those problems for the company, you will be able to negotiate much higher pay."

Want to earn more money at work? Take CNBC's new online course How to Negotiate a Higher Salary. Expert instructors will teach you the skills you need to get a bigger paycheck, including how to prepare and build your confidence, what to do and say, and how to craft a counteroffer. Pre-register now and use coupon code EARLYBIRD for an introductory discount of 50% off through Nov. 26, 2024.

Plus, sign up for CNBC Make It's newsletter to get tips and tricks for success at work, with money and in life.