You can broadly classify words in the Japanese language into 3 main groups: Native Japanese words (called "wago"), kanji words that originally came from China ("kanjijukugo" - kanji compounds) and loanwords from other foreign countries.
You'll find lots of cases, like '危ない' and '危険', where there are both native Japanese words and kanji compounds of Chinese origin that express the same meaning.
Given such a choice, if you use lots of native Japanese words, your writing will have quite a soft feeling.
Use lots of kanji compounds and the writing will sound slightly sterner, but will be given a firmer, more authoritative image.
Therefore, researchers' theses, writing used in the workplace and so on tend to use more of these kanji compound words.
Sanseido Web Dictionary's (Introduction article) 'ことば百科 (Language authority/encyclopaedia)' has a section called '和語を漢字熟語で表現する (Express "wago" using "kanjijukugo"), which shows you the kanji compound equivalents for native Japanese words.
If you decide you want to use a lot of kanji words, perhaps if you find yourself writing a thesis in Japanese at some point, then this will be a good reference for you.
Let's look up a kanji compound for the native Japanese word 'さがる (下がる)'.
From the hiragana list on the right of the screen, click on the 'さ-line' ('さーそ').
'さがる' appears as the third item down on the list of entries.
The meaning of the word and its uses are written down in the '和語 (native Japanese word)' column.
We can see that there are 4 different ways to use 'さがる'.
For each use of the word, appropriate kanji-compound equivalents are also shown.
You can now rephrase sentences with native Japanese words to include kanji compounds. For example...
'血圧を下げる薬' (medicine to lower blood pressure') becomes '血圧の降下剤',
'技術のレベルが下がる' ('the skill-level decreases') becomes '技術のレベルが低下する',
'先頭を走っていた選手が3番目に下がった' ('the leading runner dropped down to third place') becomes '先頭を走っていた選手が3番目に後退した'
...and so on.
However, some kanji compounds are rarely used in everyday life, for example, words like '垂下' and '下垂', which have the same meaning as 'たれさがる'(to hang, to dangle).
Also, when deciding to use kanji compounds, you need to think about the balance between, and combinations of, native Japanese words and kanji compounds in your piece of writing as a whole.
As in the case of the first example given above, where '下げる薬' becomes '降下剤' you also have to consider changes to vocabulary used alongside your key word.
Keeping that in mind, try using this convenient feature and
you'll soon have a great stock of useful Japanese expressions at your disposal!