The best advice I can give you is to keep moving. Just like with all skillshots you will be harder to hit if you're moving. of course stay behind minions as long as you can and just pop out from the side and poke if you see a chance.
If you're a squishy support stay behind minions and poke from there.(this is expecting you're playing champs like Nami, Janna, Lulu, etc.)
If you're a tank stay in front of your adc as much as possible especially if blitz gets closer so you can take that grab, or if he gets close enough to just stop him from doing anything
Also very rarely you're gonna want him to grab you. it's a free gap closer to get closer to their adc but it's best to use your owns gap closer since blitz's grab still does damage. Plus he'll most likely knock you up right after he grabs you.
It's also very easy to tell when Blitz is gonna grab. His attempt at getting into position is very obvious so just watch where he goes. If he goes into a bush he'll most likely be at your end just waiting for you to take that one step closer to him.
So in general just keep moving, stay behind your minions, and keep your eye on where he goes.