I have a field called "rev" and it starts at 0 however I would like it to increment by 1 each time a change is made via workflow. What's the best easy to do this? Should the rev field be text and with a value of 0? I had it at numerical but it keeps coming up as "double". I tried "Do Calculation" and also the "Update". I'm certainly missing something.
I think you are on the right track.
Your 'rev' column should be set to a type of 'Number', but using column settings you can specify this field show integers/whole numbers only by setting the Number of decimal places value to 'None'.
Then, in the WF you can insert the Do Calculation step:
then Calculate CurrentItem:rev plus 1 (Output to Variable: result)
then update the current list item:
then Update item in Current item
setting the Update List Item parameters to 'Field': rev to 'Value': Variable: result
Whilst the Workflow definition will treat the field values as type 'Double' it does not affect the end result.