Start by researching on your own. There are so many online real estate resources these days.
Once you get an idea of what is out there and perhaps what price range, house specifics (how many beds/baths, how much property, how much square footage, neighborhood, etc.), then start interviewing agents. Your question is bound to attract a lot of agents who will tell you to contact them. Instead, interview as many agents in person as it takes until you feel comfortable with one who has the knowledge, personality, patience and an obvious interest in what you need/want. Do not settle or get pushed into anything that is uncomfortable for you.
All cash is great but leave room for other costs associated with buying a home (inspection and title search are important) as well as a comfortable cushion for the normal (and not always so normal) house expenses that crop up.