@snapdragongirl I'd use a collar, personally, as it gives you that small bit more control if the dog does move away from you.
With mine, I make sure they can see the bit of chicken in my hand before we start walking. When they stop mucking about and sit nicely, or come to me, they get chicken. I then quickly replace it and show it to them again.
Then I start walking keeping the chicken in my hand in whichever way the dog needs it to be (some dogs will accept the chicken is there just by the fact your hand is hanging down with the chicken in it, but some dogs [like mine] are stupid and need the chicken literally in front of their nose so you end up doing a backbreaking waddle down the road with them).
Once I've walked 4-5 steps, I'll say 'heel' and then give them chicken. Then repeat repeat repeat. The key is not to reward them after they break heel. And they will break heel and usually really quickly (cos life is super exciting). So build it up slowly. 4/5 steps, say 'heel' (or 'good heel' if your dog knows 'good' is a positive thing) chicken. 4/5 steps, 'heel', chicken. Eventually it gets to the point where the dog will understand what they need to do for 'heel' to get the chicken.
It's a bit like teaching a sit to a puppy. You get the dog into the position 'sit' and then you say the word and then you reward. Once they learn the word you give the command, they do it and you reward. If that makes sense?
Will Atherton has an absolutely brilliant video on loose-lead walking which is absolutely worth a watch. I disagree with him on slip leads (mostly because I think whilst he uses them appropriately, a lot of owners don't and they end up choking their dog so I'd be happier if he just used a regular lead) but all his advice is 100% sound on how to get a dog to walk to heel.
From all you've said about your girl (not that I am stalking you, promise) she's a smart cookie so she'll pick it up super quickly - easily in a week if you're consistent. She might still drift to the front every now and then, but it happens and as long as she isn't just dragging you along I don't think that's the end of the world tbh. 😊