Agreed in Principle on FSBO property. Now what?

[Kelvin Duen]

I recently agreed on the sale price of a MLS listed "for sale by owner" property in Philadelphia. I was able to get a good price because no agents were involved. What are my next steps? How ensure the owner doesn't sell the property to someone else as I'm performing due diligence? Who do I hire to draft up a sales agreement? Title company or real estate attorney? I'm still new to real estate investing so any suggestions/guidance/advice is greatly appreciated.