Hi Ashley, I've heard differing opinions on "beefing" up your resume. Some districts in my state (Illinois) prefer an applicant have a Master's degree, while other districts hesitate at hiring a Master's teacher because of the increased salary and cost to the district.
What state are you in? I would assume any credentials that include Math or Reading/LA can only help you...as well as a ELL/ESL endorsement/certificate. I'm just about to graduate with my Masters so I will update how the job search goes when I'm done!