When a plot is being designed the writer is taking the reader on a journey. In a novel there are steps that the hero or heroine or both must take in the journey. The beginning is well in hand but where does the writer go from there. There are a number of plot points. The story is a building of events and solutions until the story reached a conclusion. The beginning of the story stats a problem that may be resolved but lead into a new problem to be solved.
But first the writer needs to decide if the main plot is going to tell the story or if there are subplots. These subplots can strengthen the main story. The subplot may have a resolution before the main plot ends. The subplot can focus on the main character's opposite or on one of the minor characters. If the first subplot is chosen this must be established in the beginning. For example in a mystery the story is the hero's and the subplot could be the villain's or the person threatened by the event of the mystery.
The subplot can be dependent or independent. The dependent kind is often used in romances. The hero has one agenda and the heroine another. Finding a solution to their dilemma brings them together. When deciding which is the main plot and which the secondary in this point. Ask yourself this question. Who has the most to gain and who has the most to lose? This will help decide which plot ends first.
If a secondary character is chosen to be a vehicle for a subplot, these can be braided by sticking to the main plot for several scenes and then returning to the subplot for several scenes. These can be alternated but there must be a different flavor to the two.
The subplot can also show a parallel to the main plot. Both may seem to be equal in strength, almost like mirror images. These subplots may come together. part and come together many times throughout the story.
The early middle of the story is the place to establish and develop your characters and their relationships. Remember that you're building to the first crisis.