How Can You Tell What Online Jobs Are Safe Without Getting Scammed?

Most of them are scams. Check with Better Business Bureau...
www.bbb.org

If you didn't apply for the job it is a scam.  Likewise any prize you have won for competitions you have not entered.

Generally speaking the majority of online job offers are simply scams or wishful thinking on the applicants part. Sure you might have a job and be able to make a little money off it, but it's much more difficult to make a reliable income online than most people think, and most of the people telling you otherwise stand to profit from it.A lot of it's basically a reoccurring affiliate marketing program:You pay person A. To join a program to make money online, you become person B.As person B you recruit person C to join the same online money making program, and etc.If you really want to make a good income online you need to do a lot of research and put in a lot of work to do so, from time to time someone will find a "Niche" market and do quite well with there ideas, but otherwise most people working online either do Affiliate Marketing or are successful in other similar programs.It's definitely possible but don't believe everything you hear from those who stand to profit from you following there advice, and if your looking for a job with a real company that will allow you to work online I would suggest checking with The Better Business Bureau, these sort of jobs will never require you pay anything up front.Best of luck to you!