Well , it depends on the Investment but I don't really see any investment you can do apart from real estate that can be 100-percent secured . yeah you should not try any investment with the money you are intending to saved most especially online.It's not easy to remain disciplined though. I've tried it. I know of someone who is very good at it, but she usually has an investment plan for every money she earns.
Not everyone is good at investing and I lost money when I tried it.
In that case you should create a bank account without getting ATM or MasterCard and be sending your saving funds there.