Do you want your synthesizer lead sounds to soar? Grab a trick from the guitarist’s bag, and add some vibrato to your sustaining runs. And not just any vibrato — specifically guitar-like vibrato is what gets that uplift that not all vibrato provides. The specific nature of fingering technique on a fretboard means that guitar vibrato modulates in the positive phase (upward pitch only)only. Synthesizer lead tones often have similar overtones to lead guitars, and therefore you can get the same soaring effect by adding a vibrato that only modulates in the positive phase.
Note that this only relates to fingering techniques; tremolo bars on guitars can hit both positive and negative phases. And this is only a suggestion for lead, melodic synthesizer lines; more percussive sounds won’t get the same “soar” from a positive-phase-only vibrato. But to make your synth leads really sing, give it a try!