I think along with "arigato"（ありがとう）and "onegaishimasu"（お願いします）, the one other phrase that folks who want to start communicating with the Japanese should internalize is "osewa ni narimashita". That expression means "Thank you for your hospitality/help", and if you've had a service provided to you by friends or host family, this is the phrase to use.
Last week on "Uta Kon"（うたコン）during the tribute to master composer Kyohei Tsutsumi（筒美京平）, I heard a very sweet oh-so-70s kayo with that same expression as the title. One of the princes of enka, Keisuke Yamauchi（山内恵介）, and veteran entertainer Masaaki Sakai（堺正章）took care of "Osewa ni Narimashita" as this friendly song that was made by Tsutsumi in such a way that would make it appealing to kids.
But it was Sakai's old bandmate from The Spiders（ザ・スパイダース）, Jun Inoue（井上順）, who sang the original version as his 2nd single from September 1971 after his successful solo debut of "Kino - Kyo - Ashita"（昨日・今日・明日）. Michio Yamagami（山上路夫）provided the lyrics about a fellow who is going after his dreams but also gives his thanks to the people who had taken care of him in the neighbourhood such as the landlady of the boarding house he lived in.
According to J-Wiki, Tsutsumi based the song on Inoue's own character with some influence from the happy-go-lucky opening theme song to the anime "Sazae-san"（サザエさん）that he also created (good golly, I forgot about that one...Tsutsumi has composed everything!). "Osewa ni Narimashita" peaked at No. 17 on Oricon.
Tsutsumi also did right by Inoue's buddy, Sakai, by giving him his own hit single.