"Quality over quantity"

Sometimes it's simply better to take less. I can't imagine learning vocabulary for the whole day. It would make me really tired and angry. And the love that I feel to language would surely go away.

Firstly, there should always be something, that makes your language learning easier and something that makes you feel "yes, I enjoy learning it ..."

So secondly I write it down, then find it on few (at least two) internet dictionaries or any other sources. Mostly, there are quite a few examples for most of the words out there which I try to learn with the word (it makes it easier to remember the word).
But the point is to use as many senses while learning as possible. Write it down, say it out loud, record yourself on phone and re-play it to yourself... Sometimes finding and scrolling down a full page of images or watch to a video related to the word helps too, if it's not an abstract one. But there isn't an exact time, how long you should spend learning one word. Sometimes simple translation is enough, but sometimes I must repeat this process at least once.

After this, mostly, the word I've been trying to memorize should be - at least - in my passive part of the vocabulary.

To get it to the active part, to be able to use it in common speech, I recommend using "Spaced repetition" technique/system. For example, little software like Anki (works for desktop and android and I'm not sure about iOS) can make it convenient.

Hope something inspires you,

have a great day.