Avoiding “And” and “But”
It’s grammatically correct to use “and” or but” at the start of a sentence.
However, doing this gives the paper an informal or casual, conversational tone. In academic papers, it is best to use more formal choices instead.
Look for instances of “and” at the start of a sentence and replace them with other transitions such as “in addition,” “further,” “furthermore,” or “moreover.”
Similarly, replace “but” at the start of a sentence with “however” or “yet”. Alternatively, see if the sentence fits into the paragraph well without any transitional phrase at all.
(Note that “and” and “but” are entirely appropriate for joining clauses within the same sentence; this recommendation is to avoid using them at the start of a sentence.)