I've freelanced on Upwork for a long time.
If you plan on looking for gigs there or on other platforms, this is my best advice:
- Fill out your profile in as much detail as you can, list all of your successful projects if you have any, take as many tests in your relevant field as you can.
- Pick your clients and your projects very carefully, screen for the key parameters such as amount they've paid out, their rating, but also the rating they have left to other freelancers they've worked with previously. They usually leave each other comments after every project, be very cautious of comments that might suggest the client is uncooperative or behaves bad in any way. Be patient, you never ever ever want to pick a bad client. Your rating on the platform is pretty much everything, and if you get a bad rating from your very first job, you may just as well quit that platform.
- Read the project descriptions carefully, and individually craft every offer. This is critical! Nothing will waste your time like copying and pasting proposals. Take the time to review the project description and requirements, and the secret sauce: write down in several bullet points how you plan to execute the project successfully. Just tell the client if you've done similar work before and how you can see this project being completed step by step. This separates the boys from the men, and will get you the best clients and the best projects. Don't make the proposal too long though, two sentences is too little but 8 paragraphs is too much.
Good luck.