Nobody likes the job/candidate search. Hiring managers get inundated with applications, while hopefuls may feel they're flinging all their hard work into an unresponsive void. It's always been a struggle to make it to the top of the pile, but you need more tricks to do so than ever.
If you're contacting potential employers over email, your first chance to make an impression is your subject line. You've got between 25 characters (on a mobile phone) and 60 characters (not words, characters) to make yourself seem interesting, according to Business Insider. Like vintage Twitter, which confined itself to 140 characters, you have to learn how to say the most important part of your argument, quickly and concisely.
Luckily, this is a skill anyone can learn. There are a couple of different ways to workshop a subject line, and for something as important as getting noticed, workshopping is well worth your time. Go through your resume and cover letter and figure out what story you're telling about yourself. Are you selling yourself as experienced? Get the number of years in your field or position in your subject line. Were you referred by a mutual acquaintance? Include their name up top.
If you don't want to stress too much, just get the most important information into the subject line. Name the position you're applying for and include a job ID, if applicable. Keep your formatting formal, avoiding all-caps and emojis. Let your recipient know what to expect when they open your email; state an intention, if you've got room. Try listing all the words that best describe who you are, what your skills are, and what you have to offer. Look at different combinations and edit them down to the pithiest possible phrasing.
Check out some examples in Business Insider to see these tips in action. This stuff is hard for everyone, even seasoned professionals. Give yourself as many tools for success as you can, and put them to work for you.