Yes. The most important thing, no matter your preferred method of investment, is to keep your entry price point as low as possible.
Also, I know a lot of members here, myself included, keep a balance between sets to flip and sets to sit on for later appreciation. There's no real drawback for mixing it up if you can keep your price low enough.
It's certainly easier for me personally to flip sets because I can keep a steady stream of sets at very low price points, so while I might not make the most money per set, I make it quickly and often, and can turn that profit around into more sets. Heck, there's some sets I could sell to other members at MSRP and I'd make a profit because I was able to get my entry point so low.
For instance, I bought some Attack on Weathertop for $20.00 a box. I could flip that this holiday season for $45 to $55+ profit.
Compare it to a member who buys it at MSRP of $60 who is sitting on it until 2014 holiday season. Even if it doubles in value, they're only making a tad more than I am, and I made it a full year before they did, which I likely threw into other investments.
But, again, that kind of stuff only works if you can keep your price points low. You really have to gauge the kind of market you live in, especially if local retailers are your primary sources of LEGO.