Consider a function to maximize:

Plot the function to help you in estimating the guess values.

You can define guess values above the solve block region or inside the solve block. In the later case, the guess values are defined locally, within the solve block, and they do not affect the rest of the worksheet.

Use the plot to help you in choosing the guess values. The plot shows more than one point of maxima, so choose a guess value that is near the maxima of interest.

You can change the guess value to view a different local maxima:

You can use a table within a solve block to define multiple guess values that you can pass to the maximize function, and the returned result is a vector of corresponding maximum values.