Don't use SPList.Items, use GetItems() instead

private static void GetItemsFromList()

{

    //from MDSN: It is best practice is to use one of the GetItem* methods of SPList to return a filtered collection of items.

    using (SPSite site = new SPSite(webUrl))

    {

        using (SPWeb web = site.OpenWeb())

        {

            SPList list = web.GetList(ListUrl);  //my list has 2 items

            Console.WriteLine(list.ItemCount);   //returns 2

            Console.WriteLine(list.Items.Count); //returns 0

            foreach (SPListItem item in list.Items)

            {

                // will not go inside loop, because list.Items is empty

            }

            for (int i = 0; i < list.ItemCount; i++)

            {

                var item = list.Items[i];  //will cause ArgumentOutOfRangeException

            }

            var items = list.GetItems(new SPQuery());  //returns all items

        }

    }

}