British do this a little differently than in America. "I've no muffins to eat." is distinctly british sounding. Also, "I haven't any muffins."(But technically correct, even though we do *not* say that in the US). In Germanic languages, "not" comes after what it affects... In romance languages, it comes before... English is the worst mix of both, so native speakers believe that "not" comes before what it modifies even though the language is built of off German. Anyway, 80% of the time, a negated verb gains a "do". "I run" is general, "I do run" is just affirmative. "I run not" is no longer said. People expect you to start speaking in rhymes, because it sounds really really old and poetic (Shakespeare). "I do not run" is what we would say. This would very very likely be shortened to "I don't run.". "I have not eaten" would be shortened to "I haven't eaten", not "I've not eaten.". These things will be understandable no matter how you do it, but it can sound non-native..... Also "I ain't" is something you'll hear eventually. It means "I am not". It's a forceful, southern, cowboy accent.