They look really good for your first go, besides that its more about taste.
Just seen this and i kind of disagree with the suggestion using lamb casings, yes they tend to be less tuff, but as a beginner they are far less forgiving when your filling, increasing the chance of splitting.
As far as lubricant goes water is your friend here, soak the skins over night and flush through under the cold tap, when you are filling keep the skin on the nozzle constantly wet. Also make a wetter mix than the recipe says.