Today there are two popular areas of the organization flie tree (smacss, bem).
The idea is fundamentally different.
Smacss based on classical approach (breaking of the project on technology), Bem is focused on the partitioning of the project into elements and also have a huge number of tools.
All of the above matter, depending on the complexity of the project.
Development support definitely speeds up if you know what you are doing.
And also read the builders of the project (e.g. gulp)
Gulp is one of the most simple and fast.