I'm sorry, there's nothing you can do, no magic cure.
You just have to get better at it, that's it.
Just try harder, pay attention to what you're doing.
Try imagining you're telling someone what you're writing about at a particular time - say the present or past. Keep that time firmly in mind and away you go.
I believe there is a certain type of flower in the Peruvian Moutains which is said to cure "tense inconsistency".