In case it hasn't been said, logs are EXTREMELY reliant on equipment - especially weapon wise. I can guarantee you that by now, everyone in the 90% bracket have their ilvl 370-375 weapon, and are close to (if not) ilvl 370. And it makes a huge difference.

Also, you absolutely have to use pots. If you don't use pots, you'll struggle to break past 80%. Hell, even 70% is a struggle without pots sometimes.

And now for a somewhat minor variable you might not be aware of - padded runs. A ridiculous amount of people will end up with better parses than you, simply because the AST is giving them all the Balance cards, and stuff like that. But you don't have to worry about this if all you want is to get close to the 90s.

For starters, just focus on getting to ilvl 370. Get your weapon, and THEN try showing what you're capable of.