Hire a good landscaping maintenance contractor for one year. Find out what you need to do. Decide what you want to do.
With all due respect to the GOOD landscape professionals out there...my experience in my neck of the woods is that MOST folks in that business are hacks. Guys throw a lawn mower on a trailer or back of a pickup and all of a sudden they are "landscape professionals". IMO you'd do better to educate youself (very easy to do with all the info easily accessed on the web..books, etc) and find a local landscape retailer who doesn't mind jibber jabbering with you from time to time to give you some direction.
Depends on your own choices, time available, degree of quality desired, etc. If you do choose to outsource...choose someone very carefully...ask for local reference properties you can take a look at...as well as at least three customers you can contact...and then do so and ask good and lots of questions. Good luck.