When publishing a package request it is a best practice to send an e-mail to the sending sites. This ensures that the information in the request, such as the URL and Package ID, can be copied-and-pasted from the e-mail and into the corresponding configuration fields by the sending site.
Additionally, when creating the package request e-mail, you should copy-and-paste the required information from the configuration dialogs into the e-mail. Using copy-and-paste ensures that the information is entered correctly and will not create issues during package transfers.
It is also a best practice to include a detailed description of the documents and/or metadata you want to be sent. Since the sending site may not use the same naming conventions for Document Types and Keyword Types as the receiving site, you should be clear on the types of documents you want and what metadata about them you need to index them in your system.
You should also include your contact information in the request, especially if it is different from the information configured under your Site Information.