Hello
If you are just interested in the money, just work for a brickie or plasterer for a few months then pass yourself off as a tradesman. Dont become an apprentice.
If you want a career then, coded welders are highly paid. But an electrical/ instrument apprenticeship with someone like Woodside, BP, BHP etc is in my opinion the best trade career going. Good money, not hard on the body and least boring.
Instrument / Electrical if you can get in is the go IMHO been in the game at various levels for many years. If you are any good you will pickup $100K here in Perth, contracts currently around $180K for shorter term bush work then theres oil and gas start at say $130/40K sky's the limit if contracting.
If I am hiring I will always give young guys a shot that show initiative / motivation.