Hi. I too still have trouble getting Maddie to walk nicely and she's four. Bramble, on the other hand just ambles nicely by my side. I don't really understand why this is other than different personalities.
With Maddie I think it depends on the sniffing conditions! Some days she will walk really well and others she's desperate to sniff every leaf, cigarette end, and any rubbish she can see.
I do the end of the lead, bring back to my side, treat etc and she usually has to be reminded at the start of every walk. In an attempt to be more interesting than the sniffs I have just started doing this: as she walks by my side she will 'check in' by looking at me. I click or say good, make her sit then feed her three very tasty treats, one at a time whilst praising her. Walk on for only a few steps, hope she checks in again and repeat. Now I vary the treat -sometimes just one, sometimes just praise, sometimes two or three treats so it keeps her guessing! At the moment it's working well but whether she will get wise to it I don't know! I know I couldn't get her to walk well if I was with anybody else though!