My dear no matter how careful you are, the tendency of NOT falling for scam project is limited. you can not totally avoid everything. if you follow the guideline you provided, the tendency of not getting affected is high and you might succeed. i think everyone involved in crypto has been SCAMMED in one way or the other.
In reality the risk is really high, hence the more we should be careful when it comes to investing. Investing in altcoins nowadays IMO is not really advisable, unless its an old coins, already have a development and listed in decent exchanges with volumes of $10,000 and up in 24 hours.
That figure is just my own gauge or qualification in choosing an investment.