the best way of advertising for me is getting referrals from my existing clients to future clients. people talk. its probably the slowest, but its the most powerful. pretty much if your client talks to one of their friends about you, and they need a lawn guy, you are almost guaranteed the job.
long story short; do a good job each and every time at each and every yard you do, and the jobs will come to you.
My set up:
-2007 Chevy 2500hd 8.1l 4x4
-7x18 enclosed trailer
-Grasshopper front mount 61", gravely 52"
-36" Gravely Walkbehind, 21" exmark push mower