Best way to crimping the outer tabs of a Crimp Terminal Contact
The reason you are not getting good crimps is simply because you are using the wrong tool. There is no universal tool that is going to work with every type of crimp contact that you can purchase in the market place. 

Most of the reputable manufacturers of crimp terminals will also sell a hand tool designed specifically for a certain series of crimp contacts. The best of these tools are rather expensive and it is not uncommon for them to cost into the several 100 USD. But if you want to make repeatedly reliable crimps it is essential to have the proper tool. 

From a design engineer viewpoint when it is necessary to build prototypes from time to time it can be a useful strategy select one or two connector lines that you can use for the greater percentage of your connection needs and then purchase the appropriate tools for those lines.