Looking for professional references starting out in HVAC/electrical in Arkansas

Hey all, I'm based in the Little Rock area. I've got my EPA 608 Universal certification, and I'm getting ready to apply for entry-level HVAC and electrician apprenticeship positions in Arkansas.

A lot of these applications ask for professional references, and since I'm just starting out in the trades, I don't have a deep work history to pull from yet. I'm trying to figure out the best way to line up solid references before I start applying.

A few questions for anyone who's been through this:

• Does it need to be someone from a related trade, or can references from past jobs (retail, warehouse, etc.) work for an entry-level/apprentice position?
• If you don't have trade experience, is it okay to use instructors, coaches, or others who can speak to character and reliability?
• How many references do hiring managers typically want, and do they actually follow up and call them?
• Any advice on how to approach someone and ask them to be a reference?