Are we speaking about the pre-ICO phase? If that's the case then you can't really tell If the coin will be profitable but you will definitely know If the project is something serious and not a simple shitcoin made by scammers. You should always take a look at the team members, escrow, read the whitepaper and have an idea how things are going to work, how the coin is distributed among developers, community managers, investors etc.

If the coin is launched already (say you are a few months/1 year late) then you should check the previous achievements and roadmap and how active the development is. See MaidSafe for example, even though they didn't deliver the project yet, we see weekly development changes and the coin is on the top 10 because everyone knows that this team will eventually deliver and everything is on progress (Beta, alpha, Final release).

By looking at how big the coin it will last a long time and can count on in the future.
Moreover you can also find out about the type of coin you mean by often read in a forum that discusses many of the coin, so that you can know the development of coin and can be profitable in the future.

Ok just let me remind you that all ways you will get here as replies are based on their own preferences. Your's to follow.

We all know that there's no such thing to know if a certain coin will be profitable or not (unless in Bitcoin obviously). Try to do some autopsy to all branches of a certain project if they have some "things" to be considered as main ingredient for them to become success. This is a risk investment after all so you really need to spend some to see the actual journey you will faced when you invest in a coin.

This the challenge when dealing in an altcoin investment so all I can say is, accept all the associated risk once you start putting your money on a certain coin.

if i was interested in getting more money through alts i think there are only two strategies i'd use.

one would be to look for new coins that are being given away. decred did this. stellar and byteball too. no doubt there are more. screw putting money in an ico.

the other would be to spread money across the poloniex top 10-20 and pull money out when they pump. because all of them pump eventually.

it's like a stock market tracker versus trading individual shares. 99 times out of 100 the tracker wins.

The best you can do in my opinion is to make sure that the team behind whatever the coin is is actually legitimate. The more public they are with their team the better because it means they are comfortable with putting their actual real life reputation on the line for the project, and if they know that it's going to turn out to be a unprofitable or scammy project then they will still anonymous.

Most ICOs out there are for the sole benefit of the founder, little of the funds actually goes towards promoting and developing the coins but a lot of the funds collected through the crowdsale goes straght into the founder's pockets. Look for clear roadmaps.

Take a good and hard look at all the completely useless crapcoins and start thinking about it as to why there are so many altcoins on the internet? yes they all are just on the internet and you'll never find anything related to them offline in the real world that we live in unlike bitcoin with real factories and real companies.
If you are trying to live in the real world and earn some real world money seriously then bitcoin is the most promising and community backed coin you'll ever find and it's not just me saying this but the price and the marketcap can speak for itself and markets especially with $10B+ at stakes never lie.

what exactly do you call "top" because the coins in an exchange that go on top of the list are usually sorted with volume, and an increased volume in most of the cases means the coin is already pumped so investing in it means buying into the pump and being already late.

in my opinion in trading you should make each trade count. you should have a good reason for each of them. not just because it was on top.

The firth thing you should check are the developers themselves. If they have a history of scamming and fraud then they should be avoided. A good example of this is QTUM. The founder had a past history of scamming and it is known that their "successful" ICO was done because they themselves bought up their own tokens. The next phase is to dump them on us.

Based on my experience, there is no set of black and white strategies that can help determine if a certain coin can perform well in the cryptocurrency market. There are some coins that are dismissed right from the very start but which made it good actually in the market. And, of course, there are those that are full of amazing potentials that later on falter and failed to deliver the good expected of them.

I am not good at investigating cryptocoins but I always look at the people behind working for the coin as a good indicator for the coin plus there should be an existing or a ready community that can propel the coin and can guide the coin in its ups and downs. This is aside from the technicalities that we should look into.

there are some good coins under 1000 satoshi like feather coin (FTC) and it has very good price rises with good profit.
also remember than it is always easier to pump a coin from 100 to 1000 than it is to pump it from 0.01 to 0.1.

terrible advice in my opinion. there is no goo ICO project and there is no easy way of assessing them. and the main reason why an ICO is created is for the owner to make money most of the times through scamming.