Hi, I start to learn Japanese in my company office once a week, how can I learn Hiragana effectively, please help, arigato!
You can use Tinycards to reinforce your memory.
When you can recognize them 80% of the time, you can move on to learn more vocabularies, because associating the sound and meaning of words would help you make up the remaining part, which may otherwise be boring to memorize and fade quickly.
Tofugu. I learned Hiragana in a couple of days with it (http://www.tofugu.com/japanese/learn-hiragana/). They also have some things that can help you learn Katakana and Kanji, like this (http://www.tofugu.com/japanese/learn-katakana/) and WaniKani (https://www.wanikani.com/).
Here is some practice that you can do everyday along with Tofugu that will help strengthen your Hiragana and Katakana memories: https://realkana.com/hiragana/, http://www.csus.edu/indiv/s/sheaa/projects/genki/hiragana-timer.html and https://tinycards.duolingo.com/decks/e1fhs/writing-japanese-hiragana (they also have a Katakana one)
I only used this one for a short period of time, but it seemed to be helping me learn Kanji: https://kanji.koohii.com/.
I got this link from Arachnje, so tip of the hat to her: go to yamasa.org and select "kana" on the menu, and then either "hiragana" or "katakana" on the submenu. This will give you animation with stroke order for all kana, sorted by beginning letter.
Was super helpful to me, when it turned out that my new course demanded written homework (frowny face).
It's simple, all you need is some time, a page and a pencil, just try to write any word you know in japanese , don't worry about mistakes, and try to write hiragana as beautifully as you can, that worked for me. at first it's a bit hard as we start forgetting the kana, but once you have some practice you'l get familiar with kana with the rest of your life, but be careful to right in the right order
Regarding writing hirigana in the correct stroke order, I have a few tips.
Generally speaking, you want to start with the short horizontal lines, rather than longer verticals when the lines are touching each other. So if you are writing さ (SA), す (SU) or も (MO), start by drawing the short horizontal stroke(s), then add the long vertical stroke. And with と(TO), you should make the little stroke on top first, then make the big curved stroke. This feels backwards to me, but it does give you much better control of the shape and proportions of the character.
Also, most characters (and strokes) are written left to right and top to bottom. For example, when writing out は (HA) or ほ (HO), you would draw the left vertical stroke, followed by the short horizontal stroke(s), and end with the right vertical stroke. And with に (NI), you would start with the vertical stroke on the left, then do the upper horizontal stroke, followed by the lower one. Left to right, top to bottom. This is also where you start drawing, move the pen from left to right or from the top downward.
There are exceptions, but these two rules are almost always true. By remembering them, you can usually guess the correct stroke order for hirigana characters without looking it up every time.
As someone already mentioned, write the Kana's down in a sheet of notebook paper. What I did was write down one Kana in a row and completed that row with the repeated Kana. Afterwards, I go on to the next row and continue on from there.
I also recommend downloading apps on your smartphone that teaches you simple Kana characters. One that I really like is "Infinite Japanese" which basically teaches you simple words such as numbers, food, animals, colors, etc. in either Romaji, Kana, or Kanji form. There are even apps that teaches you the strokes of the Kana's.
Best of luck on your learning in Japanese!