So today I went out to do some shopping at a thrift store and I've yet to do any cold approaches yet since I'm still working on myself as a person. Anyhow, I dress fairly well and once the cash register rings me up she complimented the button top I was wearing and after saying thanks she continued by stating that I should come and bring some old attire that I do not wear anymore since she really appreciated what i wore. She complimented my beanie as well but afterwards I just had no idea what to say aside from the usual thanks and just smiling casually without looking creepy of course?

How could I have done to handle this better? I'm just horrible at small talk.