Here's some guidelines I use in investing.

Check for Insider Transactions (SEC Form 4)
This is so simple it is extremely frustrating to hear people invest without doing it. It's called 'SEC Form 4' and it is a document corporate insiders are required to file shortly after making a transaction. There are a couple places that allow you to get current copies for free... one is from the SEC itself...but a prettier version would be with sites like Gurufocus.com ...there are a number of similar sites.

The premise behind using the SEC Form 4 is that corporate officers are inherently greedy. Therefor if they buy their own stock it is very likely to go up because they wouldn't be stupid and buy their own stock when they think something is going to go badly for a company. You do have to be careful, because sometimes they are stupid and make mistakes... so if a bunch of officers are buying in the recent future it's generally a safer bet.

If You Invest in Precious Metal, Take Possession
It's been said that you don't really invest in PM but speculate in it... any case... the general reason to hold PM is to hedge against the dollar. However, if the dollar collapses you don't exactly want to be standing around with 'paper' so get the metal.

Be Extremely Skeptical About What is Touted By The TV
Watching a financial report on the news and hear someone touting some stock? Honestly I have no idea why anyone pays attention to them. In my experience those are the companies to avoid, along with 'corporate advertisements' ... you know... selling the 'brand.' Companies should be spending their money selling products, not themselves.

Be Aware of Technical Traders
I'm just starting to get used to Technical Analysis and wouldn't trade solely on it... however, to some people it's a religion so learn how it behaves so you can anticipate what the technicals are going to do to you.

Don't Use Stoploss
If you can't follow your investments enough to reexamine a stock if the price plummets you probably shouldn't be investing. Using Stoploss is an unnecessary risk because it allows short sellers to crash a stock price. Basically, a short sells a stock and the price declines steeply which triggers your stoploss and you sell your long position at a lower price back to the short. You should have confidence in your investments enough to resist the temptation to sell at a loss. If you use insider transactions as a guide there is almost no excuse to sell at a loss.