I like this Search Engine the most http://www.manufacturers.com.tw/search_ ... image.y=10
Look for Golden rated suppliers and ones that have at least one Patent for their products, find out if them OEM to well known brands, do a Google Patent search and find out if they have Assigned Patents before from Inventors.
Check them out, personaly I go on my gut feeling, by the above will reduce your risk's.
There are a lot of other search engines for Asia, but say away from these below
This is why I am personaly Taiwan Baised, and many Taiwan Manufactures have China Factories or Bussiness Partners and many products made in Taiwan have parts from China and the quality is very well controled from the Taiwan Manufacture, so yes Taiwan Products do cost a little more but you get better products and Taiwan has been making products since the 1950's mass production and Taiwan have very simular schooling system to the U.S and understand the Western people better.English is their Second Language every different to China.
The below advice is from a Australian Inventor who is in the know for these issues
The best plan is to not be too paranoid, just accept that Chinese factories WILL copy your product if there is a market for it and theres not much you can do about it, too many people sabotage their own products out of fear of copying, best to come to terms with it and just roll on unless you have mega bucks and 5+ years of waiting up your sleeve to file a PCT patent and the various national phases associated (Australia take note, the Chinese government pays its citizens patent fees, why cant the Australian government?)
So next thing to do is contact the factories in China, there are only 3 online networks I know of which care at all about IP theft with their members so best deal with them and then contact the network admins if you have problems. exportid.com alibaba.com exportbureau.com
avoid ec21.com and tradekey.com (full of counterfeiters)
I would suggest contacting multiple factories, get samples, have zero loyalty to any particular one and by process of elimination find one who can get the job done well. Honestly the copying wont start until your product becomes a commercial success by which time you should have some money to take more action.
finally be aware that many Australian inventors associations / trade fairs / and advertised inventor help business are practically a direct line to Chinese counterfeiters, same goes for the patents office itself as everything is publically published (you can bet someone is watching New Inventors every week taking notes) so theres no chance of you keeping it secret anyway, best go for maximum first mover publicity and deal with the later when you are more financially able to.