Here at ClassifiedsPH, we regularly try to keep away scam posts, but as an individual, you can also follow these steps to protect yourself:

1. Meetups are always more preferable
2. Ads from foreigners can be potential scams - To determine if the ad is a scam, you can copy the posted email or a portion of the ad and search for it in google. If it’s a scam, chances are google will return results of links pertaining to people complaining about that ad
3. http://www.youtube.com/watch?v=KKsEf2aPnms shows a useful tutorial on the subject. You can view it below.