How You Can Get Higher Salary If Your Current/Last Salary Is Low?

Write a nice proposal for readability to the people responsible for evaluating salaries.  Limit use of all first letter capitals in questions and sentences to relevant writings requiring that formatting.

Basically, state demands like a high-jacker.

• You've got to show some initiative.  Companies that rely on  long-term staff do not like to deal with turnover and want to keep loyal and reliable people to maintain confidence and smooth operations.

Demonstrate your worth with reminders, like refreshing your resume and lifestyle as it has developed with the company.

• That development is worth something and the term for it is called "goodwill" based on time investment and well-tuned operational stability in the workplace.  
• Like a marriage contribution that might involve one actual bread winner with a supporting spouse doing a bunch of seemingly intangible things to keep everything working well behind the scenes. 

Apply a value to your "goodwill" labor contribution 

• Go large on the raise so that they know you are serious about negotiating and have other options to depart if they seek to brush you off. 

Appeal on a human level about why the market makes the existing salary too low to meet your reasonable living standards.  

• As you have developed more social esteem working with the company, to meet status demands and uphold the valuable nature of the position for the business, a salary increase is commensurately due.  

Show them how their alternatives to your mainstay contributions pale in comparison.

• At least six-months of training a new secretary to just get the sub-surface mechanics of the position worked out.
• Shocking clients with point of contact change-over.
• Shocking work environment with new employee integration.
  • Stick them with some statistics if they want to brow-beat you for asking for more money.

Finally, ask for an assistant, 'at the very least.'

• This is a frivolous request and should scare them into realizing they either pony up with higher salary or face onboarding additional staff.  
  • If they call your bluff and want to hire more staff, they will have to increase your salary for training that person also.
• The request shows that you do not harbor paranoia about controlling all of your work tasks and evidences that your work demands have escalated disproportionate to your salary.