If you didn't get a promotion in 2017, or if you're hoping to get another one in 2018, making a plan to get ahead now is a good idea. Getting a promotion doesn't happen instantly, often it takes months, or years, to lay the groundwork. Career coaches and authors recommend setting up a meeting with your boss in which you make it clear you'd like to talk about your performance and compensation months in advance. But even before you set this meeting, you want to make sure you're ready to present your best case. If you're ready to take your career to the next level in 2018, there are a few strategies you can start developing now.

1. Carry yourself with gravitas

According to best-selling author and CNBC contributor Suzy Welch, to get ahead, you need to act professionally and come across as in control of your career. "You can showcase gravitas in voice, language and attire," she says. "But most of all, through the way you comport yourself."

CNBC Contributor Suzy Welch CNBC | Mary Stevens

Welch describes this elusive characteristic as a mixture of "seriousness, maturity, thoughtfulness, wisdom" — traits that are tough to fake and that will lead your boss and colleagues to respect you and give your perspective greater consideration. You can also cultivate gravitas, Welch says, through the behaviors you avoid, like gossiping, being unprepared for meetings, interrupting others or improvising important presentations. "Learn when to talk and when to listen respectfully," she says. "If you're not sure about something, ask a good question."

2. Set reasonable expectations

Make sure you and your boss are on the same page about what's expected of you and what your top priorities are, says Rosemary Haefner, chief human resources officer at CareerBuilder. "Clearly communicate the details of your assignments so your boss is more aware of what is on your plate," Haefner tells CNBC. "You cannot assume that your boss understands the hours associated with assignments. Making him or her aware will help create mutually agreeable expectations." Don't be afraid to check in frequently or ask questions along the way, she says. "Remember that it's a team effort to reach goals," the executive says, "with your boss as the lead person."

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3. Prioritize your tasks

"Shark Tank" investor and real estate mogul Barbara Corcoran has a simple strategy for making sure she's on top of everything she has to get done. "I make my to-do list at night, transferring items I couldn't get done that day," she says in an interview with Inc. Magazine. "I rate the items in order of importance: A, B or C." And be sure to keep a list of your high-priority tasks in a place that's visible, says Craig Jarrow, author of "Time Management Ninja." "If you don't regularly look at your list, you might as well not keep one," he writes on his blog.

4. Automate your reminders

Assign yourself calendar reminders to make sure you don't forget anything. "Calendar management is the single most important thing, especially as you get busy and have more responsibilities," the CEO of J.P. Morgan Asset Management tells CNBC. "Unless you can stay on top of that religiously, it will end up owning you, and that's not a way to go about staying organized and being on top of things."

5. Take initiative and over-deliver

Once you're meeting deadlines on time and consistently presenting great work, don't be afraid to seize the initiative. Present a new idea to your boss or offer to help on different projects. "Getting promoted is not just about doing your job," says Welch. "It's about over-delivering, which involves rethinking the way you do your job." If you want to show your boss you're ready for that next step, she says, then "you're not just going to do what's asked of you and what's expected of you. You're going to expand your job to help the company [and] help your team." This is an updated version of a previously published article. Disclosure: CNBC owns the exclusive off-network cable rights to "Shark Tank." Don't miss: Successful people share how to get more done in your 24-hour day