So much helpful stuff has already been said, so I'm going to focus on CV and job applying stuff...(I'm a Director at my company and do the hiring stuff for entry level and junior hires alongside my main role). We don't have lab roles, but speaking to friends, a lot of my experience seems to be common, so hopefully this is helpful.
We advertised at the start of the year, and our successful two people started in March. I regularly wish I could speak to the ~200 people who applied and tell them some very valuable information (well, I think it's valuable - appreciate not all of them would think it's valuable....).
This is what I would say....
"110 of you sent in your CV when our job advert says to use the application form attached. Why did you do that? I didn't even look at your experience and skills, as I now know for sure that one of them isn't attention to detail and focus. Your application was immediately moved to the rejection folder."
To the ~90 who did the application form (and before anyone comes at me, the form is super basic - just your details, a short statement about what you'd bring to the role, and then space for education and experience. The main reason we do it is to make sure everyone answers the same questions for a level playing field, plus we can output these to a spreadsheet and review them far more easily)....
"Around 20 of you wrote a statement that is over 100 words. We explicitly say the answer has to be 100 words only. Did you know, we didn't even look at your application?"
"Of the 70 who sent in an application that did what we asked for....many of you couldn't use the main word for our industry in the statement or refer to it in any way, so your application felt irrelevant. We really just need someone to be able to show things like 'your company is an estate agency....I would like to work in a estate agency' (for example, but it's amazing how simple it is to show that you know what the company does and say you'd like to do that).
"Of the 30-ish who genuinely got down to our shortlist, we then looked carefully at education (yes, including degree classification), work experience, and your statement in more depth. None of you were excluded (for interviewing) for one SINGLE negative thing. Some people with lower degree grades got through because their 100-word statement really captured what we do (they'd read our website.....), or because they had really interesting work experience; or, interestingly, because they had work experience that wasn't very relevant to ours field, but they'd made it relevant in the description of their role, and showed the transferable skills."
Appreciate this is long, but what I'm trying to say is that some (not all) employers aren't asking a lot - they just want applicants to show that they understand the kind of role they're applying for, can write a line or two about their skills, and show (not tell) attention to detail and focus.