To initially gain skill it might be best to start with making iron [[bowl|bowls]]. Granted they're not worth much to traders and are useless except in altars, but since each bowl is 0.3 kg, they don't use that much lump and they're made from a readily-available substance (iron). The exception to this is if you have access to a vein of gold or silver, in which case rings are the better choice, both in terms of value and lump consumed.