I think the hardest thing really is understanding that you aren't going to be a millionaire over night. And, it's also difficult to get everyone to take you seriously. This is especially the case when you see businesses with new trucks and fancy equipment all over the place- they can be a bit intimidating.
The first thing I went out and did was had business cards, tshirts and signs for my truck made. this way I came off more legit. Insurance also helps- and discussing that you have insurance with your clients and offering to show them certificates of liability coverage as well.
My work stood for itself- I took pride in what was performed and made sure that they saw that. I was always on time and if I told someone I was going to do something I did just that.
I also did some bartering- I traded lawn mowing for a season with a friend of mine in exchange for a basic website: www.icutgrassllc.com
You have to think outside of the box.