is there any true legit site where you can really earn big cash?

I don't know any legit site that can earn big cash. But there is a site called microworkers.com where you can earn fast money instead of big. You do small tasks there like signing up to a website, liking facebook pages, posting photos and etc. And the earnings for those task are only a few cents but when it adds up to $9 you can withdraw the money.

Have you any specialized skill?

If the site pays in big cash amount you usually those sites are scam. So be careful before you join to the site. You should already make a good investigation before you join in.

Any program in which people can earn big cash needs an investment to start with. If you are new to earning money online, I would suggest that you start slowly. Earning online is a business, just like an offline business. You need to know what you are doing. My suggestion is to stick with MyLot and build up a good reputation. I do have another program that is on my profile, if you like to post on forums. It is an honest program, although it doesn't pay a lot, it is a good way to get started online. And, of course, so is MyLot. It does take time to build an online income. Be wise and keep learning. All the best to you.