Address the client by name, if you can find out what it is. Often it's in reviews from past freelancers. Most freelancers don't do this, so it can make you stand out.
Don't talk so much about you, what you do, how much experience you have, how awesome you are, etc. Clients don't really care. Instead, from the very beginning, focus on the benefits that clients are looking for -- not what they will get from you, but the results that will come from what they get from you. Then, explain briefly what it takes to achieve those results. This will show your expertise without you having to actually talk about it.
If you include portfolio samples, do so in a link, if possible. Sometimes attachments can be missed. And don't tell clients to "check out your portfolio." You do the work and include the most relevant samples for them.
Always answer additional questions first. Clients actually see these first, so you have to make them count or they won't read the rest of your proposal.
I could go on, but I suggest you do some reading on the Upwork blog and here in the forums so that you can get a good understanding of how things work here and some helpful tips. You'll save yourself a lot of time and trouble!
I like the Kanye rap idea!
My question is, how can I ask questions before writing a proposal? I want to know things before I bid on something. What area of science is the paper on, length, speaker's native language, audience, etc. Many of the jobs listed don't include much information at all.
I'm totally TOTALLY new. I respect all of you and ask you to gently point me in the right direction. Thanks!
re: "My question is, how can I ask questions before writing a proposal?"
If you see a job posting that doesn't have enough information for you to be able to send a proposal, then that job is not for you.
Don't worry, though, there are other freelancers who know how to work with clients like that. They will do the work.