Flashcards - little cards or pieces of paper - can be very useful for language study. You write a word or phrase to learn on one side and the meaning on the other.
When learning a language you must practice with longer dialogues or texts, but sometimes you just want to memorise individual words and short phrases. One way of learning words/phrases is to memorise word lists. This has several drawbacks:
Step 1: Get some cards. blank business cards - sadly, Dymock's bookstore in the city no longer stocks blank business cards ; 'visiting cards' - newsagents may stock blank cards, e.g. corner of Miller & Ridge St, North Sydney has 76x45mm cards, packet of 50 for AU$1.55 (made in Indonesia, hopefully not from a rain-forest!) ; cut up thick paper or thin card - Thinner paper works, but the cards will wear much more quickly.
Step 2: Fill out the cards. Put words/phrases on one side of a card, and (English) meanings on the other. If your subject language has a simple alphabet, you can put several words/phrases on one card, e.g. a list of colours, weekday names, compass directions, all the forms of a particular verb. For ideographic script (e.g. Chinese -- see below), just put one word/phrase on each card.
Step 3: Get something to hold the cards together. A growing collection of cards can blow off your desk or run loose in your pocket/bag. Rubber bands work well. Blank cards are sold in a small box, but a box can be a nuisance if you like to store & retrieve cards quickly. I usually carry 20 or so cards loose in my top pocket.
You can try printing flashcards using a computer, but it's a lot of work getting tables to look right in a word processor, getting front/back pages to line up etc. The problems are compounded for ideographic scripts.
Alphabets represent sounds (at least vaguely), but ideographic characters don't, so there are 3 items (meaning, sound and writing) to put on your 2-sided cards.
You usually learn the sound of a new word/phrase before learning to write it. Create a card with just the meaning and sound (in pinyin, kana or [yuck!] romaji) and you can practice with it right away. Example: side 1. A sample sentence using the word may help.
Later, when you learn to write the word/phrase, add writing to the back of the card. For a single character, hints for writing and/or a reminder of the stroke order may help. Example: side 2.
Practising with these cards is easy. Just look at the meaning (or sound, or writing), being careful to keep the other information covered. Can you remember/guess the other information from what you're looking at?
Japanese is trickier - kanji (singly and in compounds) typically have many readings (sometimes with different meanings) and many words have the same sound. For individual kanji and words, it's probably best to list the several readings on the one card.
Reminder: don't just make cards with single words - use longer phrases as well.
Some suggestions for getting legible ideographic characters onto the card:
China Books (Shop F7, Level 1, 683 George Street, Sydney - up the escalator in an arcade near the Marigold restaurant in Haymarket) has cheap Chinese stroke order dictionaries. I bought one (新华写字字典 on the spine, Xinhua xiezi zidian on the cover) a year ago for AU$12, but the website catalogue says its now AU$11. The catalogue lists another book 'Common Chinese Characters Stroke-Order Dictionary' for AU$9. Don't buy one if you don't need it - if you're doing a course then your textbook or course notes may be all you need.
Mingti2L If you attempt making your own cards with a computer, use a font that looks like neat handwriting or brush-strokes - avoid blocky fonts. An example is the freely available Chinese font Arphic PL KaitiM [link to a zip file containing several publicly available Arphic Fonts]. Also beware the many weird and wonderful ways software and fonts support (or fail to support) pinyin characters - typically the tone marks are very small and hard to read.