When choosing where to trade, do not rely on any site that can't point to a 100-percent unbiased guarantee. Regardless of what they call it, you only want to trust a website or service that ensures your best interests are front and center. They should commit to everyone that they will not trade in the shares they tell their customers about, and that they're not simply touting their own investments.

Most Wall Street pundits will tell you it's impossible to time the stock market. While it's unrealistic to think you'll get in at the very bottom and out at the very top of a market cycle, there are ways to spot major changes in market trends as they emerge. And by spotting those changes, you can position yourself to capture solid profits in a new market uptrend and keep the bulk of those gains when the market eventually enters a downturn.
Berkshire Hathaway -- Berkshire Hathaway is a conglomerate with more than 60 wholly owned businesses, including household names such as Geico, Duracell, Dairy Queen, and many more. The company also has a massive $230 billion stock portfolio, much of which was hand-selected by Warren Buffett, arguably the most successful investor of all time. Berkshire specifically targets businesses and stocks with durable competitive advantages and has a fantastic 55-year track record of executing on its vision of using its businesses to generate capital to reinvest in other businesses and stocks.
In contrast to finding an expert or two that seems to make valuable and careful decisions, do your best to avoid listening to share market 'tips' from friends or work colleagues. Typically these people will know less than you and have very little to base their suggestion on. No matter how well meaning it may be, advice from someone who knows next to nothing about the topic in question is not advice.
A stock's market capitalization (cap) is its true value, the sum of the total shares multiplied by price. It has more meaning than the share price because it allows you to evaluate a company in the context of others of the same size in its industry. You can use a market cap as a filter to screen for companies to balance your portfolio. A small-cap company with stock capitalization of $250 million to $2 billion shouldn't be compared to a large cap, which ranges from $10 billion to $100 billion. Market capitalization influences your investment returns. 
In the professional world, one of the key concepts is diversification. Harry Markowitz is a Nobel prize winning economist and one of his major discoveries was that adding new asset classes can dramatically alter the overall risk profile of a portfolio. His finding was that a portfolio that contained very low risk assets would normally benefit from lower volatility and higher returns if a higher risk asset was added. This is due to the likely lack of correlation between high and low risk asset classes.
Since the underlying businesses operate in differing markets, sectors and countries, their quoted prices move independently as supply and demand in them rises and falls and new information is released to the public about the current business situation. It is the changing of prices that offer investors the opportunity to make a capital gain (or loss) via ownership.
Dollar-cost average: This sounds complicated, but it’s not. Dollar-cost averaging means investing a set amount of money at regular intervals, such as once per week or month. That set amount buys more shares when the stock price goes down and fewer shares when it rises, but overall, it evens out the average price you pay. Some online brokerage firms let investors set up an automated investing schedule.