Would it be better is I ask you before I post something that is questionable?
If you feel it's questionable, then it is very likely something you shouldn't post. As you said, stop to think before you post, and you'll be just fine.
Captainsticks already listed the areas I think you could improve upon in terms of posting.
And as others have mentioned, I don't believe any of your posts have actually been deleted. They are likely just not where you posted them and have been moved, or merged with more relevant threads.