yesterday I was cheated by this MEW address user:0x83ecb676706aa5c7cf72384723935dd1195dcb3e He/She sent my 0.2549 Eth from my ETH Wallet address :0xe6b0d7f7d18c14015d47ecc77cf5c0009f34bb18 Shit!!! when the scammer know my private key by cheating to make something like https://www.myetherwallet.com/ front page.Can we add more steps than using only private key to make the scammer can not access my wallet again and again
No way, you'd better to use new wallet and should use MEW with metamask or with cold storage for more secure.
MyEtherWallet has notorious click-click-click process telling you what you should do whenever you enter their homepage. It gives you a lot of good tips and hints on how to secure your account. Furthermore, when starting to enter your private key on their website it specifically tells you "this is a bad idea".
As you are probably aware of currently, you should always be very careful with your private key and double-check everything. And yes, for example Metamask is a good addition to security.