Thanks for your interest in contributing to this project! The typical contribution process is outlined in order below.
First off, see if an ask for a similar change has already been raised in the Github issue tracker. If so, feel free to add a comment if you have new content to contribute. If not, then please just add a supportive emoji to an existing comment to avoid cluttering the discussion with "me too" comments.
If there are no existing issues related to your desired change, then create a new one with a clear description of the problem you want to solve. How you want to solve it is optional.
If you don't intend to actually make code changes, then you're done.
If you want to do the work yourself, then please make that clear in the issue discussion. Ideally you'd get agreement/alignment from the repo maintainer before starting work to ensure you're aligned with the goals of the project and not wasting your time, but that's up to you.
Set up your dev environment per https://github.com/dvankley/firefly-plaid-connector-2#development.
As you're working, try to break your work up into meaningful commits. That is, each commit should represent a logically distinct chunk of work with a meaningful commit message. Try not to put a ton of work in one huge commit, or push lots of small "typo lol" commits if you can avoid it (although we've all been there, I'm definitely not above it).
Once you're happy with your work, you should run it against your local Firefly/Plaid setup to ensure it does what it's supposed to.
Please ensure you have some automated test coverage for your change if at all possible. Bonus points for looking at actual test coverage numbers and ensuring your change at least doesn't decrease the coverage percentage. If a framework doesn't already exist for the test you need to write, feel free to ask for help.
Open a pull request with your changes.
It might take a few days, but I promise I will get to reviewing it at some point. I will try to be as polite as possible, but please don't take review feedback as personal criticism. As long as we're aligned on the goal and overall approach, we'll get it merged eventually.
Here's an example of a very good PR: #96