Leverage is an agreement between you and your broker where he allows you to open a trade size bigger than what your account balance would have originally permitted, under the conditions that the trade(s) will be closed if your losses cause your account balance to fall to zero or any amount fixed by the broker.
So, a 1:3000 leverage means the broker is willing to allow you open a trade 3,000 times more than what your account balance would have permitted. But remember that if your losses on the trade become so much that your account balance is approaching zero, the broker will forcibly close the trade.
So, when using high leverage always keep some extra money aside, so that if your account balance is getting to near zero, you can deposit more funds into it to prevent your trades from being closed at a loss.
For me, I don't even let the losses to pile up; once I open a trade and it doesn't yield profit in the first 10 seconds i close it immediately and cut my losses. There is no need to keep a losing trade alive while hoping that you will get lucky and it will turn to a winning trade.
Kill the trade if it is not yielding profit a few seconds after you open it, there will always be another trade. By doing this you keep your losses low.