I rarely talk about production technics in here, but I'll tell you my opinion about EQ... its not much, but its a little something I have learned . Yes, mixing is an art. Some Engineers out there are PRos and they bring life to your track. You are so Lucky to have FL, cuz this little program happens to make things very easier with all those nice presets and FX. However, You can do a nice lil mixing, but it wont sound like those real masterboard in the studio. People over there can spend H-O-U-R-S mixing the same track. They even spent DAYS, cuz at some point, the ear get tired. They have the accoustic needed ($$$$$) to have that nice sound. For now, FL can do something very nice and simple, but its not about what exaclty frequencies you put here and there...each tracks are different. You just do it like you paint a nice draft. Its an art of the ears. I dunno if you have that already, but get yourself some nice Headphones. You can find Nice ones for $60 and up.
"Listening" is the best way to learn. Listen to accapellas, instrumentals especially. Study them. Listen to how they pan some instruments to the left to the right, how they have put stereo effects in the main samples, layering the kick till they sound tick.. .etc.
If you use samples, its one thing , your drums is something else.. and if you use Instruments/Vst made with a keyboard , its another technic.
I personnally cant stand a bassline made in Fruity. I loove the real sound of a bass. If you dont mind using FL for your bassline, Put a lil "porta" it can help... Layer your bass and put a filter in your second bass. Playyyy with your stuff, dont be scared to try. I dont know, Ive noticed that the bass is sometimes same volume OR LESS as the kick and the vocals. anyways, just take your time to LISTEN, you'll see. Theres a lot of songs out there with the BEST mixing. Your like WOAH! Collin parks beats are a nice examples. Imagine how his music could sound wack without EQ. I was wondering for a long time who are they engineer.. but they are great.
IF nobody want to tell you their tricks, just listen carefully to the mixing of ANY songs. You'll get some answers hopefully..