When writing kanji, those pictograms you typically see in Chinese and Japanese, the order you draw the strokes is important. There are basic guidelines you can follow. Kee’s studying basic kanji at the moment and I have joined her studies since I think it wouldn’t hurt to practice more Japanese. She got this cute anime poster with stroke order hints.
However, as in all languages, there are subtle exceptions. Consider the kanjis for left and right, 左 and 右, respectively. The order of the first two strokes is opposite for each as you can see in the following picture.
An easy mistake to make. I bet a lot of Japanese get this wrong often.