Unopened games should have their ROM and save data dumped before attempting to play them. This avoids inadvertent modification of the data and helps preserve any possible rewritable data in its unused/“factory” state. This is especially important for types of cart that store the ROM on rewritable media, or games that come with special save data pre-installed. But it is not necessarily possible to know in advance, hence why its advisable to dump first. Note in your submission whether the physical media was sealed and include a photo of the cart/packaging in its sealed state, if possible.
You should clean the physical media's electrical contacts before trying to dump it, then dump it, and if it doesn't match something in the database, clean it again and dump it a second time, checking if both dumps match using a file comparison tool or calculating the SHA256 of each file and comparing those values. This helps ensure that dirt on the contacts is not causing interference, and that dirt was fully removed during the cleaning process.
Especially for rare items, make sure to keep the media and dumping hardware around as long as possible (and keep in contact with any future owner if possible), in case an issue with the dump comes up. At minimum (again, if possible) its good idea to keep it around for a while after its been added to the database.