Every Friday, after I get paid, I take out $40 cash and put half in one envelope, half in the other. Once I get a good amount, I'm going to research the banks and find the best interest rate on CDs. Then I'll invest them both - but with different expiration dates.
I use this plan for future expenses. I'm saving up to take my nephew on a Safari in Africa. We won't be going for at least six years, so that gives me time. CD's are safe, and I can't get at them until a specific time. I'll make sure I can get at the other CD after a year or so - for emergencies.