When planning a unit, it is important to think backwards. Begin with the end in mind.
The first thing you do when planning a unit (after looking at the curriculum) is the pick your culminating activity and/or decide what skills will be tested on the final test.
Once the end is ready, you work backwards to figure out how you will get your students to the point where they'll be able to successfully complete the culminating activity.
Next, when you have decided what skills need to be taught, you can put your lessons together, planning how many classes the unit will take, and keep your year-long plan in perspective.
This is a simple, way to get a cohesive unit plan instead of a bunch of lesson plans on a similar topic.
Please comment or send your questions to me at firstname.lastname@example.org
Have great day!