You should start with the problems you can solve.
If you go straight up this street and over the river, you will enter North America.
I’m sorry, but I have a prior engagement with my ex-boyfriend today, so I can’t meet up with you.
The kanji and the word are exactly the same. That means they share meanings as well.
Since this word is made up of a single kanji, it should use the kun'yomi reading. When learning the kanji, you didn't learn that reading, so here's a mnemonic to help you with this word:
When I think about the word "previous" I think of the beginning of a TV show where they say "previously on..." Let's go with that.
Previously on Lost (or some other show), everyone gets stuck inside of a sack (さき). Imagine all the characters in the TV show writhing around inside of a sack, trying to get out.
You can differentiate this from 先ず (まず) because it doesn't have a hiragana add on. It's plain. It's boring. It's just a sack (and also means the same thing as the kanji it comes from because it's a single kanji with nothing attached, which gets you to previous, which gets you to さき).