Chinese dictionaries index the entries by Radical (部首) and Strokes (筆劃)
The character 人 is also it's radical. It is listed first in the 亻radical section
人
Radical: 亻 (#9)
Stroke count: 2
The radical of the character 仁 is 亻 and it has four strokes, therefore, it is listed after 人 in the 亻 radical section because 仁 has two strokes more than 人
仁
Radical: 亻 (#9)
Stroke count: 4
The radical of 靈 is 雨 which has a stroke count of 8, therefore, it is listed far down after 亻 on the radical list
The character 靈 itself has 24 strokes and would be listed far down in the 雨 radical section
靈
Radical: 雨 (#173)
Stroke count: 24
It is not as efficient as The Alphabetical indexing system but it is what we have. The major problem of the radical-stroke count system is the users need to know the radical of the character he is looking for. If you don't know it, you can't even start to search.
Even when you knew the radical and started your search in the correct section, you still need to spend some time looking up the character from a long list of characters that are arranged by ascending stroke counts order
If you can memorize all the radical numbers e.g. 亻(#9); 雨 (#173). You can find a character as quickly as using an English dictionary to search for an English word