I have no credit history at all. What's the fastest honest way to start?
Start with a tool built for exactly this: a secured credit card (you put down a small refundable deposit that becomes your limit) or a credit-builder loan from a credit union. Both report your on-time payments to the credit bureaus, which is what actually builds a score.
Then keep two habits boringly consistent: pay the full balance on time every month, and keep what you owe well below your limit. There's no secret fast-track, and anyone promising to “boost” your score for a fee is selling something you can do yourself for free.