If you haven’t already realized this, the reroll affix option is heavily weighted. D4Craft, of craftofexile has now made an occultist calculator which reflects those weights. Some combinations are nigh impossible, so it will save you a ton of money, and mats, to run your items through the calculator first. Just go to D4craft.
Just as an example, it will likely take around 20 tries to get movement speed on boots, so don’t even bring boots to the occultist if it doesn’t already have movement speed on it.
Instructions on how to use the calculator.