Transistors functionality is dependent on application.What are you using it for ? What voltages are applied and how much current is pass through the transistor. For example your BC547 has a maximum voltage rating of 50V and a maximum current that can pass through ("Drawn by the load ") is 100mA.
The Hfe (AKA beta) is the gain of the transistor .Many factors can alter the gain but for simplification yours has a "Gain" of 110 to 800. Which is to say that the current passing from collector to emitter is 110 to 800 times the current at the base. Sometimes there will be a letter following the BC547 like "A" ,"B" or "C" This is the hfe classification .This means for example that a BC547A will have a hfe "Gain" of between 110 ~ 220.
So in "Common Collector" mode if 1 mA is applied to the base then the transistor will pass current across the collector to the emitter between 110ma - 220 ma which would ,of course, exceed its maximum current capability.As you can see it doesn't take much current at the base to drive current across the collector and emitter. So it won't take much to burn out a transistor quickly.You also need to remember that the current at the emitter is the current at the collector Plus the current at the base . An easy solution is to place a resistor at the base that limits the current to the base.So as in Ohms law Voltage divided by the Resistance equals the current that will pass across the resistor to the base of the transistor.
You have to consider that current requires a Load.Load "draws" current.And the transistor can also be considered a load at the base.So by using a limiting resistor, the base will only "draw" as much as the resistor will allow.So if your supply is 10 volts and you place a resistor of say 100K ohms at the base then there will be 0.1 mA drawn across the resistor to the base. So 0.1mA times a "gain" of 110 equals 11mA from the collector. And 0.1mA from the base plus 11mA from the collector equals 11.1 ma at the emitter. No matter how much current is available from your power supply that transistor will only pass 11.1mA.
Other modes include Common Base and Common Emitter which have different functions .
Playing with transistors can be very interesting. Even blowing them up is educational because you can see limitations and what can happen when limitations are exceeded .Failure can be as informative as success.Just wear eye protection.
Without getting in a conflict about components from Ebay .I know from experience that they're just fine and have always matched design parameters.The only time they fail is when I've done something wrong .Digikey is a good source as well ,but the shipping charges is what puts me off.Maybe it's better in the States I don't know.
If your interested ,as ledtester mentioned,there are inexpensive transistor testers from Ebay available that are good starter tools for the novice .They will tell you what pins are what and the "gain" .Plus they will test other components such as diodes ,capacitors and resistors .Very handy tools.