This recipe will show you a few tricks you can use while painting with stamps.
To get ready you will just need to select a stamp that you would like to use and make sure it is enabled.
The following steps will help you obtain straight lines on curved surfaces (paint mode):
1. One trick you can do to get straight lines on a curved surface, such as the stitching or lettering on cloth, is to select Flatten to UV Space in the Mesh menu. Keep in mind this will only work when using paint tools. Any sculpting you do while the mesh is Flattened to UV Space will go away when you Unflatten from UV Space.
2. Next you will select your desired stamp and set the spacing to what suits your purpose.
3. Also, you will want to make sure your UVs are laid out in such a way that any line work is not on a diagonal. This will cause aliasing issues meaning your straight line will look jagged as shown in the following screenshot: