Me newbie, can point out what is meant by newbie mistakes?
Maybe newbie is the wrong description? More accurate would be "attitude"
You have to decide whether you are an investor or a trader. As I am an investor my time line is longer. Compared to a trader who has a faster turn around time i.e takes profit quickly. The disadvantage with being a trader is the higher transaction cost & studies have shown that they don't make as much $ as investors.
My most successful investment is Apple & it took a long, long, ... time to mature. In fact I have kept some of my Apple shares for 15+ years & am now collecting dividends from these shares. I had used Apple products & had followed their products so I knew something about Apple products.
I did buy share of products that I didn't know about e.g. Lucent & lost money when the shares fell. Why did I buy Lucent? It was because everyone else that I knew was buying them :o So at least understand about a company's product before you buy their shares.
I spend $ like a poor man & not like spending is going out of fashion. Started by buying a few stocks & avoid putting everything you have into one or two stocks. Having a reserve of $ will ensure that you will not be forced to sell at the wrong time. You will also have $ to buy shares when everyone else is selling at a loss.
For me investing can be an iterative process. You buy & then keep the ones that perform and sell the ones that perform less. Maybe I could have avoided some of the mistakes if I had started to subscribe to publications such as IBD(Investment Business Daily)?
Be patient because stocks may take time to go up . They are like people, when they reach the growth stage, growth can be explosive. When stocks start going up wait for a retracement & then buy some more.