Just a little bit more on working for free.
Apps on the iPhone are pretty damn cheap. Many are free. Some fantastic ones are free actually. But invariably the free ones have much more one-star ratings (or even no-star if that's possible). This happens no matter how good the app may be.
Often, the more expensive an app is, the fewer one-star ratings it gets.
People pay for things they value. But it works the other way around too -
We value that which we pay for.
So, on the app store, it's easy to see how that works. People download a free app, load it up for thirty seconds (if even), don't instantly get hooked and then delete it, which hitting it with a one-star rating. If they've paid a tenner for that app, it becomes worth their time to really try the app out, get used to it, see if it has more to offer than it appears on the surface. By dumping it too early, they could miss out and lose the investment they put in to pay for it in the first place.
The same is true for employment.
If someone has invested even a week's wages on you, they'll be more likely to put the time into teaching you what you need to know. More likely to pay attention to what you do. More likely to look for the value you bring.
Less likely to give you that one-star rating.
And less likely to dump your sorry ass out on the streets.