All my new words are written on paper, in my A4 ring binder, and I will review them sometimes. The more I review them, the better. After that, I put the new word with a picture in a flash card program (called Anki) and this is done on this computer. This will then be copied and transferred to my mobile phone, so I review the picture (to remember the word), or I review the word and guess the meaning. Sometimes, for difficult words I will add a description in English. For difficult words, I will write it on a small piece of paper, maybe 15 difficult words for the week, and I will think about how to remember each one, and I will read this paper several times at work each day. After 3 or 4 days, I ignore the paper. The Anki program on the phone chooses the frequency of words to review. So in summary, 1 - all are written on paper, in a folder. 2 they are uploaded with a picture to Anki flash cards, and reviewed each day, or as frequently as the program says. 3 the most difficult words go with me to work on a small piece of paper and I meditate on them and think of how to remember them.