Great shoes and boots can last for years, and when they finally start to decline you'll find small tears or seams that start to come apart. Use popular DIY silicone putty Sugru to repair small problems with your shoe uppers.
Instructables user projectsugru demonstrates howhe use Sugru to repair a damaged seam on his favourite boots. He colour-matched Sugru sachets to his boots so the repair was less obvious (the photo above is meant to show the Sugru, but the photos in the actual repair use the colour-matched version) and then used small amounts of the substance at a time to repair the seam. Full instructions and step-by-step photos can be found at Instructables at the link below.
Keep in mind that you won't be able to repair any problems with your shoe's sole using Sugru according to the author (although I'd probably give it a try anyway) and while Sugru bonds with most materials including cloth and leather, shoes can be made from many fabrics; it's possible it won't work with your shoes.
How to repair your boots using Sugru [Instructables]