Generally, one set of slashes or brackets would be used, with or without spaces in between the words.
As far as whether you should use slashes or brackets, generally slashes suggest a broad transcription, meaning you're aiming more for showing phonemes than exact phonetic detail, whereas brackets suggest a narrow transcription, meaning you're aiming to show a lot of phonetic detail, regardless of whether any of the phonetic traits form natural classes.
In actual practice, neither slashes nor brackets are actually necessary if it's clear what type of transcription you are going for and can even be something to avoid depending on how you feel about the theoretical foundation of the phoneme/phone distinction.
This is a good example of a transcription of more than a single word by a well respected phonetician: John Wells, Three Cheers
If you're writing something for a publication, however, I would follow that publications style guide. If you're writing something for a class, I would follow the instructor's preferences.