This is my latest article featured in the Financial Mail section of the Mail on Sunday - http://www.dailymail.co.uk/money/
Sadly, the simple answer is that you cannot, unless you have very deep pockets.
This is especially true if your idea is based around the provision of new and improved services. You can be sure that your existing competitors and new entrants to the market will try and copy your ideas, once they see they are popular and profitable.
To counter this you must have additional service improvements ready to be launched as soon as you see competitors beginning to catch up. Constant innovation is a fundamental part of entreneurship; some might argue it is also its most enjoyable aspect.
If you have a great product idea you should always take expert advice from an intellectual property lawyer about patent protection. In the first instance it is usually possible to receive some free advice and then to put in place basic and inexpensive protection in the UK.
Later, you need to be wary about spending too much money on trying to protect your idea all over the world before you have proved there is a significant market for your new product. But even if you decide to do so, it is always very difficult to take legal action against unscrupulous manufacturers in distant markets.
My advice for aspiring inventors is always to secure a strategic relationship with a reputable organisation locally that has a genuine need for the business benefits of the product that you are proposing.
They are very unlikely to behave unethically as it would swiftly damage their reputation in their local marketplace if they were seen to be exploiting inventors and engineers. They should also have the deep pockets that can protect your intellectual property, if necessary.
Inventors by nature are often solitary people who can find it difficult to work in teams and accept the guiding hand of authority. This can lead to trust issues, which is why finding the right strategic partner is of the utmost importance.
When the relationship with the supplier is working well, it becomes more like mentoring, where clever people with good ideas for new products are nurtured rather than exploited.