There is not a single best way.
If you plan on living in the house FHA or 203K loans are good, low down payment, 3.5%.
Conventional is probably out since the house must be in livable condition before the lender gives money. 20% down payment
Private Money could be next, 0 - 8% rates (local investors, Friends & Family, even Investors on BiggerPockets, etc.) 30% down payment could be required
Local Banks, Credit Unions are a good source.
Portfolio Lenders would be good also 7- 10% rates, most don't require income verification but almost everyone checks Credit with 660+ being the average. 30% down payment could be required
Then there is Hard Money 10 - 16% rates, fees/points, not sure on the down payment
Brief Overview of Financing:
The Best Beginner’s Real Estate Investing Course Online
Module 6: Real Estate Financing
I've been working on Personal Lines of Credit, Home Equity Lines of Credit, and Saving up Cash this will help with down payments, and Rehabbing, etc.
I'm currently working on Portfolio Lenders to fund the rest of the Flip, or Refinance,even thinking about having them Fund the Buy & Holds and then refi afterwards.