Any startup founders/co-founders, I'm curious to know if there are any good serious websites that offer explanations on various aspects of running a startup and common pitfalls and the like. I've looked at some but I figure it would be best if anyone who has done it before could redirect me to something :)

Not a founder but investors can be like Magpies.

Better idea: Go to startup events. In bigger cities there should be a few of them. There you can test your idea/pitch, network and get to know people which can tell you this or that.
But a lot of things you'll learn while doing :)

Serious answer: Unfortunately, there's none, but the best way I've found is to look at multiple sites, and take what they say in common. The thing is: the startup world is extremely dynamic, so advice that works in one place doesn't in another, so the advice will even be conflicting. Take it with a grain of salt and unless there's heavy opposition to what you wanna do, do it anyway, as the success of the startup is directly tied to your vision. Just because that one guy succeeded doing x doesn't mean you have to do it if you don't feel it's right.

Better yet, you can check an exact concern (eg, COO in startup team) and see the response (in this case: run away), usually these responses are more in line with each other.

If you're looking for reasons why a startup fails, a study conducted on a huge number was done and the reason for failure documented (a quick Google should lead you to it). The number one reason turned out to be founder disagreement.