Here is my 2 cents for what it is worth.
If you have the flexibility in your 401k, it probably makes sense to look into index funds and Vangard is probably a decent place to start.
However, I think you can actually do the best if you invest directly in company stocks. Utilities are pretty safe and usually pay a decent dividend (though they won't look that great if you simply look at the chart which won't show the yield from the dividend) which is reinvested in buying more stock in a 401k.
Don't make a big research project out of it - you will get analysis paralysis.
Utilities are very safe and larger companies like Boeing, GE, etc are reasonably secure. Stick with companies you know something about and diversify.
Unfortunately, it seems like investing in financial companies is a good plan since they are being subsidized by our tax dollars (bail out, sweet FDIC insurance deal, and protected from their criminal activities by the "too big to fail" attitude the gov has assumed - HSBC should be out of business, but the gov only fined them five weeks profits for laundering billions for drug cartels).
Outrageous HSBC Settlement Proves the Drug War is a Joke | | Rolling Stone
I am shooting for about 50% index funds and 50% stocks.
Lastly, try to be wary of acting out of emotion. The market is pretty strong right now and seeing the performance over the past quarter often causes us to think "now is a good time to invest" when the market is likely to go back down a bit. There is no secure way to predict this, but if you have a decent sum of money to invest, it may be a good idea to spread investing it over time like putting 1/6 of it in the market on the second Wednesday of each month for the next 6 months. On the whole you are as likely to lose as win with this approach, but it does avoid the risk of investing it all into the market at the peak before an adjustment.
