So starting a sentence with a conjunction is not a problem. In fact, you can even start a paragraph with one.
The only remaining question is whether to use a comma after the conjunction. The answer is no. But sometimes the conjunction may be followed by a truly parenthetical element surrounded by commas, coincidentally making a comma necessary after the conjunction. If you are putting a comma after the conjunction, make sure the phrase or clause after the comma is truly parenthetical.
Check the comma used in these sentences:
In sentence 2, the comma after the conjunction but is there because of the parenthetical clause. If that clause were not there or were not parenthetical, there would be no comma.
Summary: You can start a sentence with a conjunction, and you should not put a comma after the conjunction. If there is a parenthetical phrase or clause after the conjunction, there might coincidentally be a comma there, but that comma is not due to the conjunction.