Invention Promotion Firms assist inventors by providing guidance on developing, patenting, and marketing their inventions. They offer mentorship, connect inventors to networks of manufacturers and investors, and help navigate the complexities of intellectual property. 

A reputable firm will be transparent about their services, fees, and the scope of their assistance. They will have a track record of helping inventors and offer clear contracts outlining their commitments. Researching reviews and seeking references can also help determine credibility. 

No firm can guarantee success because the market viability of an invention depends on many factors. However, IPFs increase your chances by providing expertise, resources, and connections that help you make informed decisions and navigate challenges. 

Costs vary depending on services offered and the firm's structure. Some charge upfront fees, while others work on commission or royalties. It is important to understand all fees before committing and compare different firms to find one that fits your budget. 

Many firms have expertise in international intellectual property laws and can guide you through the process of securing patents in multiple countries, ensuring your invention is protected globally.