Look out for mould
Depending on the starter you use, the sausage should bloom, usually whitish coating on the outside of the sausage. Any furring can be wiped off with a piece of kitchen roll soaked in vinegar. Discard sausages that are black or smelly, oozing and / or unusually soft, or have any other striking unusual colour on the surface.
Animals
Make sure the sausage is completely free from animals – rats and mice should be unable to get to the sausage, and, of course, children should understand the sausage is potentially dangerous until it is finished and shown to be safe.
A really important point is flies – they don’t care a jot about salt, so be sure to keep the developing sausages free from flying insects.
Amendments
To make a bigger chorizo sausage, use ox runner skins and stuff with a spoon. You will need to double up the quantities, and you could add some other ingredients
2 teaspoons of fennel seeds
2 teaspoons of oregano
2 teaspoons of cumin
1 teaspoon of chili powder, or flakes
The drying of ox runners is slightly different in as much as the sausage is thicker, and consequently the centre should be really firmly cured.
By elena merlika (Tapas bar a Madrid)
By MOs810 (Own work) [CC BY-SA 4.0 (http://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons