There is no single optimal workflow for editing your video projects that fits every case. Although there certainly are some specific use cases; e.g. tutorial editing, wedding videos, …, some agreement exists about distinguishing four basic activities.
Montage: starting with your raw footage, you’ll have to deliver a coherent and fluent succession of strips that tell your story. Clips have to be rearranged, combined, split (cut) and trimmed.
Effects: these can be simple transition effects between strips, e.g. fade or full-fledged animations, e.g. rolling end credits.
Color grading: because your assembled timeline consists of different shots taken with different cameras under different lighting conditions, colors can vary widely between them. With color grading and color correcting you can harmonize the color perception.
Sound: this ranges from adding background music and voice-over to creating special sound effects and using third-party software such as Audacity.