Well, Wealthfront has been great for me. I made about $395 in interest alone last month. There's no minimum to start, you can literally start with 50 bucks. You collect interest monthly. I'm a bit risk averse, so to me, at the moment, a guaranteed 5% return on my money is better than a "maybe" 7% return playing the market - over the long-term at that.
Do your research and you'll see that you'll be hard-pressed to find many people complaining about Wealthfront. Most of the online reviews for Wealthfront are excellent.
It syncs to your regular bank account, you can't open up a Wealthfront account without one. Start off small, every paycheck put 25-50 dollars in, more if you can. You'll literally make money while you sleep.