I don't know if it's gonna be helpful but let me just tell you something: I started learning Japanese two weeks ago (or three?) and I've learned Hiragana and Katakana so far. And I didn't make any flashcards. But now I'm about to start learning kanji and I think I'll need them. My mom is learning Chinese and she bought a set of flashcards. On the first side they have kanji character and one, whole sentence in Chinese and on the other side there is how you should read it and the translation (of the character and the sentence). She says it's really helpful in learning not just one character but more and more different sentences. I think it's a good way to study a language.

I recommend to learn the Kunyomi (original Japanese words) as words, not as Kanji, on their own type of flashcard, esp. for Kunyomi combinations like 明日. It doesn't hurt to have a few examples of such words on a flashcard for a Kanji, but that's not what you should learn. What you should learn for each Kanji are the meaning(s), the Onyomi (Japanized Chinese syllable readings), and the parts (some people do that with mnemonic sentences). So 明 means "bright, light", it consists of 日 "sun" and 月 "moon" (because both give light), the Onyomi are "mei,myou,min", and examples (use those you have encountered) for Onyomi are 明治 "Meiji era", 説明 setsumei "explanation" and 不明 fumei "unknown". All these use "mei", so for me, I learn "mei" as the most common Onyomi and the others as additions (which may change when I learn more words). 明らか akarika "obvious, evident"; 明るい akarui "bright, cheerful", 明かり akari "light" and 明日 ashita "tomorrow", 明後日 asatte "day after tomorrow" go on different cards. You can see the root "a-" in the forms "aka-" and "asu" in these words, and also the connection to aku/akeru "to open" (夜明け yoake means "dawn"). So all these are genuine Japanese words, no matter what Kanji they got assigned when the Chinese writing system was used for them because the Japanese had not invented one of their own.

Each Kanji has multiple pronunciations! Usually 1 or 2, but sometimes more. 明 by itself is pronounced mei, ryou, or min. But has different pronunciations in other words, such as akarui and ashita. So when it's combined with another kanji you can expect it to take an a or aka. If you make flashcards, I would suggest putting the Kanji on one side, then the different pronunciations. For example, 後 on the main side, then ato and go or kou on the other side. Then put example words that use this kanji under them. Such as Ato, Ushiro, or Nengo. An app would be very helpful. Kanji is hard, good luck!

Have you thought about using sites/apps like memrise.com ?