Standing in your wave really helps mitigate his q potential. If you stand behind the minions, right as his q starts to pass them move forward, he'll have no chance to hit. As lulu specifically, hold your e for when he e's, it's crazy hard to consistently shield off his q damage, and either way you'll still run oom first.
Adc choice plays a big role in velkoz vs enchanter supports as far as lane dynamic. If you've got a Draven into vel's xayah, you want to match velkoz on lane side and sit even with your Draven. This way, your adc is free farming and can create his own pressure, while you nullify velkoz (unless your draven sucks, in which case, good luck lol).
If your adc is weak and theirs is non-pressure strength (your twitch into their Cait) you want to match lane sides with the enemy adc. You're not going to out harass velkoz, but you can make free trades while the enemy cses with e + auto, then when they step out of the wave follow it up with a q, hopefully that hits both adc and vel. Keep up the pressure there and you can match vel's lane pressure on your adc.
If your adc is weak and they have strong with pressure (Draven, trist, good kalistas) then match the vel so your adc can cs easier, shield off what damage you can, and cry softly till midgame. Lulu doesn't have the ability to 2v1 that kind of lane, and so you have to play to your strengths and buff your carry up enough to actually carry fights. Losing lane gracefully is a serious skill that will climb you a lot.
If you have any specific questions, let me know!