• Open your Supabase project dashboard.
• Head over to the "Storage" section in the sidebar.
• Click on the "Create a new bucket" button.
• Give your bucket a name. Make it unique and descriptive.
• Decide if the bucket should be "Public" or "Private" based on what you need.

• Go to the "SQL Editor" in the sidebar.
• Use SQL to set up your storage policies. For instance, if you want the bucket to be readable by anyone but writable only by authenticated users, use:

-- Allow read access for anyone
create policy "Public read access" on storage.objects
for select using (bucket_id = 'your_bucket_name');

-- Allow write access only for authenticated users
create policy "Authenticated write access" on storage.objects
for insert using (bucket_id = 'your_bucket_name' and auth.role() = 'authenticated');
create policy "Authenticated write access" on storage.objects
for update using (bucket_id = 'your_bucket_name' and auth.role() = 'authenticated');

• Swap out 'your_bucket_name' with the actual name of your bucket.

• Make sure Row Level Security (RLS) is turned on for your storage policies.
• In the SQL Editor, run this command to enable RLS:

-- Enable RLS on storage.objects
alter table storage.objects enable row level security;

• Check that RLS is now active for your storage bucket.

• Depending on your security needs, you can write extra custom policies. For example, to let users manage their own files:

-- Allow users to manage their own files
create policy "Users can access their own files" on storage.objects
for all using (
  bucket_id = 'your_bucket_name' and auth.uid() = owner_id
);

• Replace owner_id with the column that stores the owner’s ID.

• Upload files to your bucket and try accessing them with different roles (e.g., unauthenticated user, authenticated user).
• Check that the access permissions match your defined policies.
• Use the Supabase Auth features to test how authenticated users interact with your storage bucket.

• Regularly review and update your storage policies based on changing security needs.
• Keep an eye on access logs and audit trails to make sure you're following your security standards.
• Adjust your SQL policies or add new ones as needed to boost security.

Make sure your storage setup always follows best practices for security and fits your app's specific needs.