For instance, if you are writing about cars, you could use a synonym like “vehicle” or be more specific e.g. a Ford Fiesta. Sometimes you need to rewrite a sentence entirely rather than using a replacement.
Also, be careful to avoid starting consecutive sentences in similar ways, e.g. “there are” or “it is” – or using someone’s name.
I’d always suggest reading your copy aloud as you are more likely to pick up on this happening.