Hello and welcome to Gitcoin fellow user, as you may or may not know Gitcoin is such a beautiful place where you can sharpen your skills while contributing to making projects better and of course earning some money (which is always nice!).
You will need Metamask as it is required to interact with most of the site features, specially when applying for bounties or funding issues.
Funding an issue: as a developer you have a bug/want a feature on your application but don't have the time or don't have the skills to do it? Simply post a bounty in less than 90 sec and you can rest assured it will get solved (sometimes in record time!).
Applying for a bounty: you have the skills, you have the time and you want the problem to be solved because down there you know it's bugging you. Apply as a contributor, increase your skills and have fun while doing so!
Read the bounty details, if it's unclear what you need to do, drop a message in the Github issue so the user that funded the bounty can post more details about the issue.
You want to apply but don't have any ETH to cover the fee? Use the Faucet.
Don't get mad when the funder picks somebody else to solve the issue even if you were the first to apply.
There are cases when the funder have a deadline, stick to the deadline. If you are unsure you will have it ready before it, don't apply as it will be just a waste of time.
Let the funder know if you won't be able to solve the issue.
Keep the funder informed about what you're doing to solve the problem.
After submitting a PR, don't spam the funder. They get a notification and will be reviewing the PR as soon as possible.
You will get paid once your PR solving the issue gets merged, unless the bounty details says otherwise. Don't get desperate asking for money after submitting a PR.
If you need help, the Chat might be useful.
Have fun, improve your coding/design/etc skills, make Gitcoin a better resource!