I do investments for a living. I manage people's savings and retirement investments. I manage a fairly big dollar amount (but that doesn't mean I'm better than anyone).
Basically, what you wanna do as an investor is take as much risk as you are comfortable taking. If down markets have you anxious and wanting to bail out of the stock market, maybe you shouldn't be 100% in stocks over the long haul. Making big changes in asset allocation costs investors about 2% return each year ("Irrational Exuberance", "Psychology of Investing"). So, if you weren't comfortable with the market swings you may wanna reduce your % in equities, but I wouldn't do that until at least the middle of February if you did.
If you're young and have less than 50k invested, you might as well be 100% in stocks though because you do not have "a lot" to lose. Once you amass a greater amount of money to the point that you are nervous about losing it, then maybe scale back and add in some bonds, real estate, and cash.
I think you're courting a bit too much risk by focusing (100%?) on materials stocks (do you mean trucking & rail by "haulers"?).
What I try to do day in and day out is get into areas that have a good risk/reward picture. If some thing has run up a lot, I'm going to trim back or sell; if an area has come down in price or hovered for a while, then I may investigate.
I think funds in general are a good way to invest since the manager of the fund is going to make adjustments to market conditions. As long as you aren't chasing hot returns by moving money to and from funds, you should do all right. With individual stocks, if a given one represents more than 5% of your portfolio, then you are generally taking on too much risk (Modern Portfolio Theory). As investors we wanna get paid for the risk that we take.