I agree with the first reply.

But I'll also give you one or two tips. Do some research, make a list of coins that have potential real-world use and value. Avoid the sh1tcoins.
Then when you're looking to buy, buy coins from that list that are sitting below their usual cost. If it's a good coin, and it's cost is lower than it usually is, buy it. Sell it when you make a small profit. Some profit is better than no profit.