For now I'm more recommending buying when on a private sale or during the IEO
Binance, Huobi, Gate.io, these exchanges are very good to follow, the average project that holds an IEO there always ends successfully trading above the IEO price
If you are able to be lucky and have the opportunities to invest during the launchpad then it's very much anticipated that the chance of getting decent profits is there for you when you work with binance, IEOs that being held inside this exchange have a higher chance to grow in value after the launchpad has ended, it's a chance that shouldn't be missed by any investors to take place.
When the token you invested in belongs to a very good project, it has all the chances to go up. Therefore, it is evident that the token sale price will be more profitable. When you do not want to lose, you can invest in this altcoin later, when you finally understand that it is not any kind of a fraud or scam. Here, everything depends on the project.