Hello, as someone usually on the other end my advice would be to first start with credible sources. These can be some of the gig platforms like Guru and Upwork. However, you may want someone more local in which case search for a local developer meetup. Contact the group and ether go to a meetup and meet some of the companies and independent developers or ask them to announce/post an ad for you in their group. Doing this will get you known local developers with a good reputation. It is always best when possible to have someone you can meet with face to face and see the same thing on the same screen. With that I would recommend that some of your requirements for taking on a team or developer is that they use a source control system like git, offer frequent updates (weekly or bi-weekly) on the status of the project and who have examples of previous work along the lines of what you need done.
As someone who has bid and applied for positions like yours I would be happy to help you evaluate teams and developers for making your choice and even help you locate some in your area.