Jay,
That depends on how you are accessing this list. If it is in a group and you are querying the group, the group owner can change the method of sorting the items when the group is viewed. If it is in the group that you link to your Featured Content or Gallery Content, you have the ability to also change the sorting method. But if you are talking about having your item show up first in a search, then it will be dependent on the search parameters that you use to find it. Search results are shown by default in order of "Relevance" - essentially by how closely the title and tags align with the search parameters.
If it's in a group and you really need it to be the first group item displayed, then I would recommend altering the title of the item so that you can sort alphabetically. Your other options are Views (which will change based on popularity), Owner (most likely irrelevant in this case), Rating (which may change based on popularity), and Date (which changes each time the item is modified).
If it's being discovered through searches, then you should think hard about how people are searching for that document and use those appropriate tags so that you will increase the likelihood that it shows up first in your search results.
Heath
