We've just had a huge bubble in crypto. At some point a down-turn will occur. I think there's a fair chance we're into that now (though of course I could be wrong). If so, it means easy money will be very much harder to make :( If we are into a down turn then I personally won't be thinking much about buying in the near future (other than some icos possibly). I would basically wait until it looks like either the down-turn has ended, or we get another crash which would provide a quick opportunity to make money on the bounce-back.
Regarding which coins to buy I have no idea. Also much more difficult since the poloniex trollbox is no longer around! Maybe there are other troll-boxes or you could scan all the various forums :)