Effects is a pretty broad term, just about anything can be used as an "effect".
I tend to spend a lot of time on effects in my tunes, what I'm looking for are sounds that complement or distract from the different movements in my main instruments, building tension and release. So; say I'm high passing all my drums in a part, filtering them out with automation, in my mind it's like they're disappearing upwards and your brain expects - especially if you're filtering out all the audible sounds at the time - the sound's going to come "back down" again, ie the HP to open up and the drums to become more and more audible through the high frequencies down to the lows, but if you smack a low passed something or other into the mix it's like you're riding a new rising wave, but where the first sound (in this example the drums) seemed to disappear from the "surface" of the track (ie no filtering) into the air (HP) the new sound comes in with an opening low pass filter, so it rises, but from "below" and when fully open it emerges, so to speak, and then you might bring the drums right back in again, with no filter and you've created a little moment of surprise. (The sounds disappeared upwards, then new sounds appeared from below to suddenly be joined by the old sounds again.)
Did any of that make sense?
I think the most important thing to think about is in what direction the different layers of the tune are heading, I'm kind of hung up on these filter sweeps and things at the moment, all the time trying to direct the listeners' attention at different elements, surprising them and really taking them on a proper journey through the tune - sometimes at expense of actual musical fidelity and mixdown, but as long as I'm learning something along the way I'm happy every tune doesn't sound just right - at least I've got some new tricks up my sleeve for when I make the next one, maybe experimenting less and being able to focus on making it a proper tune.
Hope that was of any help at all.