Although your concept of learning words in context (here: in sentences) is already good, my suggestion would be to not use a ready-made source of phrases but try to find such phrases in texts you read (and find interesting / pleasant / intriguing), note them down and memorize them (e.g. on flash cards).
Why do I recommend this?
Because that way a) the process of finding and noting down itself contributes to your multifacetted learning, and b) not only do you see your new words in the context of a sentence, but also the sentences in the context of a text on a topic (and this being a topic you find interesting).
This should ensure the most robust learning effect.
(One could call this "embedded learning". I don't know if the term exists, it just came to my mind while conceptualizing the idea.)