Which types should my Entity Framework repository and service layer methods return: List, IEnumerable, IQueryable?

I have a concrete repository implementation that returns a IQueryable of the entity:

public class Repository
{
    private AppDbContext context;

    public Repository()
    {
        context = new AppDbContext();
    }


    public IQueryable<Post> GetPosts()
    {
        return context.Posts;
    }
}

My service layer can then perform LINQ as needed for other methods (where, paging, etc)

Right now my service layer is setup to return IEnumerable:

public IEnumerable<Post> GetPageOfPosts(int pageNumber, int pageSize)
{ 
    Repository postRepo = new Repository();

    var posts = (from p in postRepo.GetPosts()  //this is IQueryable
                orderby p.PostDate descending
                select p)
                .Skip((pageNumber - 1) * pageSize)
                .Take(pageSize);

    return posts;
}

This means in my codebehind I have to do a ToList() if I want to bind to a repeater or other control.

Is this the best way to handle the return types or do I need to be converting to list before I return from my service layer methods?