Recently picked up venom. Having to of fun but can't handle his primary

Hey guys just wanted to start by saying I'm having ALOT of fun on this character. Jumping in and out disrupting the BL is amazing.

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I have a really tough time hitting his primary.

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Often I struggle judging the distance. Sometimes it seems like my tentacles go right through the target when I'm to close. Is there an optimal range to use those on?

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It seems I have to be super precise with little to no room for error. Do u have any tips?