if you don't know anything about trading it is better not to do this either.
because it is not as easy as you may thing. you have to find out why there was a dump and make sure that there will be a pump after that and the price don't go lower than that.
Its a big risk to judge pumps and dumps especially in altcoins, but if you are trading bitcoins then you can identify what will be the next scenario according to the current trend.
I don't think it's a big risky, you just have to invest in solid projects and wait until the price goes where you want, invest in multiple projects, so if one fall, you can cover it with anothers... Just don't believe in projects that promise "change the world" and everything will be fine.