Considering the aspect of "Learning Vietnamese"
From the outset of my 'dabbling' in the language, I have had to consider the important aspect of whether or not I should move on from dabbling to learning.
What practical use would it be? I currently do not know as of yet, as I will reserve judgement about thinking about going to Vietnam until after my dad has gone and come back. Furthermore, there are no Vietnamese people in my immediate vicinity.
What motivation would drive me? The language - although seeming quite alien with the tones and the sounds - seems to display some logical linguistic aspects that I wish English had (e.g - no verb conjugation). Also, as the above question is above left unanswered, my motivation drives from the desire for a challenge, and the wish to experience a vastly foreign language, for theoretical purposes.
However, I still have much to consider, as I don't want to pick such a language on a wimm, only to lose what motivation I have due to the alien aspects which are foreign to native English speakers.
Any and all Vietnamese speakers (both native and non-native) are welcome to help me in this time of decision.
If you're not entirely sure you can dedicate yourself to learning a language, either continue dabbling - but maybe do it a little more often/thoroughly - or try "fully" learning it for a while with the mindset of, "Well, if I lose interest, I can always maintain what I've already learned and go back to dipping in and out of it, and at least I've had fun". Unfortunately I can't give you any concrete advice as my motivation for learning Vietnamese is literally "it seems fun", and that's enough for me lol.
But, I guess you could try learning a little about Vietnamese and Vietnam if you're still really unsure what to do. Do you find the history interesting? Does the culture grab you and make you want to experience it firsthand? Do you have an interest in folk tales, or literature? Any of those things would be a "good" reason to learn a language, regardless of how hard/easy/familiar/different it is, and they would all help you to build particular goals that would help keep your motivation. (Interested in the history? Learn about older forms of the language and read some classical texts, or read a history book in Vietnamese! Interested in the culture? Travel to Vietnam! Interested in literature? Read a ton of books in their original language! etc.)
It would be "Xin lỗi". In Vietnamese, " l " is never used as the last letter in one word.
Hope it will help you in writing, especially how to type the tones in Vietnamese: http://www.omniglot.com/writing/vietnamese.htm
And I recommend you try to read more Vietnamese stories (for children, or something like that), and hear them on Youtube or podcasts. That is good for you in writing, listening and pronunciation Vietnamese. You can try one in these sites:
http://www.seasite.niu.edu/Vietnamese/Guide_to_Pronunciation/pronunciation.htm (for Northern dialect)
https://www.livelingua.com/project/fsi/Vietnamese/ (for Southern dialect)
Good luck! - ℵ