First, I add a light reverb on my drums, starting with the snare. My drum reverb is light, but depending on the track, I might bring out the snare a little more, like if there was a rim shot or a finger snap, I'd make it real wet.
With the keys, guitars, or sample, I first check if they're thick enough. If I want to thicken em up, I would send em through a voice doubler or maybe pan it all left, then send it through a delay with like 10-20 ms and pan the effect hard right.
If the melodies are short notes, I may add delays to trail em out. Sometimes 1/4 note delay on the right side, and 1/8 note on the left, with a longer feedback.
With vocals, I start with the hook. The hook should sound much wider, or fuller than the verse. Depending on my panning, I'll do a number of things with hooks, from pitch shifting to delays to reverbs, or just panning.
With verses, I tend to leave the vocals dry, as to avoid confusing the listener. If they're not thick enough, I'll thicken em up with some light reverb or maybe delay, or voice doublers or pitch shifts in a duplicate track, but usually they remain dry. The simpler the music is, sometimes the simpler the effects are. Sometimes the music is so simple that I have to do something phoenominal with the effects. And if the music is too complicated, I may back off on effects to avoid adding too much to the song.
As for bass and kicks, I only add reverb when the music is simple, and the bass notes are simple. Most likely, I'll back off on the reverb completely with the bass and kick.
Just a simple start for me... it's ALWAYS different when I mix. It always depends on the project, and what the artist (or I) want(s) to accomplish.