More often than not, you will want to create a basic timeline for your problem ancestor. Start with information about all of the events in their life, including their birth and death dates, any marriages, birth and death of any children, the death of a spouse, and death of parents. You might also want to incorporate relevant information about the locations you are working with, for example, boundary changes.
You may choose not to indicate the source to begin with or you may use footnotes to cite the source. Creating footnotes in a spreadsheet program cannot be done with ease so you may want to include a short source reference instead.
One of the other uses of a timeline is to help illustrate instances where two people may have been combined. You can usually see this by just looking at the dates and locations and notice that something does not quite add up.
In addition to helping solve tough genealogy problems, this type of basic timeline is a great tool to keep handy when doing research. There are multiple ways to approach timelines and with our Skills-Building: Breaking Down Brick Walls course you will learn more.