How to know if a job posting is a scam?

Recently been offered a job with a tiny company (consists of 2 people) and just want to know how I can find out more information about it. I've spoken with the president/founder several times on the phone and we met at Starbucks for a couple hours to talk more about the job. He definitely knows his stuff and he showed me what kind of projects I'd be working on. It's a work at home job and since it's just two of them, they don't have an actual office. I've checked out their website and have google'd the president/founder's name. He told me he was VP of another small company previously, which I was able to find online. I've also spoken to the other employee of the company who is relatively unexperienced and was in the same position as me when hired (straight out of college with no experience). He's been there for 3 years now.

They haven't given me a reason not to believe/trust them, but I just want to make sure I'm doing everything I can on my end.

By the way.. the interview process was rigorous enough to where I feel it's a legitimate position. I submitted my resume over three weeks ago. Had an initial phone interview shortly after that lasted about an hour and consisted of standard interview questions and technical questions (wasn't too difficult but was relevant to the position I was applying for). I was then given a technical test by e-mail to do (a small programming assignment). Once I finished that, I was to contact him and walk him through my submitted answer. A week after that, we met face to face at starbucks for more questions and history/background of company and more info on position. We also agreed that I should talk to the second employee in case I had questions for him.

No reason not to trust them, if you ask me. At the worst, you get two weeks of experience, even if you don't get paid. If they say they'll pay in x days, give them x+7, and then forget it.

It's been a while since I've been a new hire but my only concern is them getting too much of my personal info, I guess. Don't you have to fill out some forms for tax purposes that will contain a lot of personal info (like SSN?).

Have you talked with the second employee yet?

Yes. Talked to him today for about an hour. Like I said, I don't really have a reason to doubt these guys. The second employee happily answered all my questions, and I felt like he was very honest with me. I think I'm just being super paranoid.

Try googling the names of the CEO and the other employee. They could be a startup that is growing. .