There is a balance with small businesses of helping let people know you're in and available, and giving them prime parking.
You park within distance of the building and visible, but not directly outside if possible.
I've actually recieved calls about whether I'm open today, because my car is in the shop and thus the parking lot is vacant.
Something as simple as not parking right in front might not make a huge difference, but that mindset, compounded over months and years, will.
Also, psychology is weird... if there are a bunch of spots near to your business pick one reasonably close but always leave the best one for customers - if there are cars parked close to the entrance but the best spot is open then customers will walk in with a bit of a buzzing high from managing to nab the primo spot. Aaaand if there is a tree that drops crap during spring/fall, park under it so no customer gets stuck with sap on their car since that can colour their entire interaction.
Isn't psychology fun!