Many of the job skills employers look for do not require expensive training or degrees. But some invaluable work skills that are key to landing promotions can be developed on your own. Here are five key skills that will pay off handsomely:

Concise communication

"People who can make a point in as few words as possible are terrific candidates for management positions," said Igor Kholkin, an operations manager with marketing company Coalition Technologies. Kholkin suggested reviewing each of your messages, and trim them of all the "fat." The remaining message should include all of the important details to be conveyed in as few words as possible, he said.

A high 'emotional quotient'

"The millennial workforce loves leaders with a high EQ, which leads those who possess it to be promoted into managerial positions," Kholkin said. A first step to improving this skill is learning to objectively identify your own emotions — and how they affect your behavior. "You can then apply this knowledge to identify others' emotions, how to empathize with them and work with them."

The ability to influence

"With this skill, the best team leaders will be able to motivate their teams organically," Kholkin said. But remember: True influencers are looked up to, not feared.

"Volunteer to take on the hardest tasks, or be the one to give a pep talk during a challenging stretch in a project. Inspire the team by being the first one to spring into action," Kholkin said.

Being positive

If you are not always as positive as you think you should be, there are ways to turn that frown upside down. The Mayo Clinic listed habits that can help build this key skill, including the following:

• Check yourself for negativity often.

• Be open to humor.

• Live a healthy lifestyle.

• Keep the company of positive people.

• Practice positive self-talk.

Tracking everything

Don't wait until just before your review to track which deals you closed or what projects you finished. Create a spreadsheet and set up columns that track all of your accomplishments. Make sure you list the details, like dates, and explain how it helped the company. "This gives you a lot of leverage when it comes to negotiating your salary," said author Graeme Austen.