Someone told me that just follow the development of the coins. Bitcointalk is already a good forum to check every coins because they all have announcement threads here. Just check it everytime and I am sure you can tell yourself if the coins are not scam and profitable.
Good idea! If you want to know what coin will be profitable is to exloplore some discussion and read more comments in altcoin section or maybe ask in some tips on veterans on trading. Furthermore, I think to determine the profitable coins is knowing if that coin has a high volume.