When it comes to crypto exchanges, theres always some risk involved, no matter the size.  How much risk you wanna take on depends on your personal preference.  For me, I tend to stick to the bigger more established exchanges that have been around for a while.  Yeah, some of the smaller ones might offer fancy bonuses or whatever to get you to sign up.  but you gotta wonder if they really have the infrastructure and track record to keep your funds safe.

As for those crypto giveaway things or earn free altcoins promos, Id be real suspicious of those.  Some shady exchanges try to reel you in with the promise of easy money, when really they just want you to deposit funds so they can take the money and run.  So yeah if something sounds too good to be true, it always pays to do your homework and make sure an exchange is legit before sending them anything.