Get good glass first.
Canon 50mm 1.8
Canon 28-105 3.5-4.5 II USM (MAKE SURE IT'S THE "II" version!! The other versions are built like shit)
And basically any of the other canon primes. Canon also makes a super old 100-300 L zoom lens, which is awkward to use cause it's a pump zoom but it's tack sharp.
is a great site for used gear; I've bought multiple things from them. Even their "bargain" rated stuff is totally useable.