Nice, if you max your HSA and your 401(k) Kudos!
If you can do both of those....making some assumptions here, you are only paying around 8% total in taxes between fed and state.
I'm not sure how the savers credit works, so that might be something worth looking.
If you end up going for an IRA (Roth or Traditional) as most people here will tell you, go with Vanguard. With such a low tax rate, I'd go with a Roth, but there might be other ways to limit your tax burden even further. An easy set it and (sort of) forget it are the target date funds. Might be a good place to start.
Other than that, read, learn, read more. You've been around the forums so you should know about Jlcollinsnh stock series, so give that a go if you have not yet.
http://jlcollinsnh.com/stock-series/