Altcoin standard evolution

Hello there!

Since there are large quantity of altcoins, do we know now a standard evolution of its trade against BTC?
i've started mining 1 month ago and most of the altcoins I have mined are going deep low.
So in fact, since I didn't yet trade them to BTC, even I'm mining 24/24, I'm losing the hypothetical BTC I would have by trade. (The quantity of BTC I was able to trade 10 days ago is now divided by 2!)

For what I quickly see the standard evolution looks like:
1) start of course at 0
2) great explosion of the price in the first weeks
3) loose stability weeks after
4) then goes slowly down to a balanced low price (probably its real price)

Of course it's just a general rule.
Mid of december seemed to be a particular event where people tried to save their BTC investisment in other "stable" coins.

The question behind it is, is there any thought concerning profitability of alt coins in long term?
Currently the simplest strategy seems to be: sell the coins you've just mined.
Perhaps the best would be: mine new coins, wait for the explosion and sell them right before the crash which always happened.

Another question is, what would be the requirement for a successful altcoin.
Noob as I am, I would say:
- improvement in term of mining compared to other generation
- good dev maintenance
- large environment of services based on this coin (trade, games, shops)

Any thought?

Thanks,
Polux