I'm slowly establishing myself as handyman/small scale contractor. I have a few clients who I've met through working what just my weekend job at estate sales. Doing stuff like loading cars gave me a chance to 1) meet clients via one on one interaction, 2) demonstrate competency (of I'll note, somewhat unrelated work, but to some extent it doesn't matter so much) and 3) give them contact information. A card is a basic but important thing to have.
I'm doing a lot of work right now that I could probably get paid higher for, but that will net me referrals, which is another large component of my growth (about half my fresh work comes from word of mouth referrals). For instance, I just did a project with a lady who seems to have many people over who took an interest in my project. I'm sure I'll hear from people down the line who saw XYZ and could use some help. I also make a point to thank my clients who refer me to others.
Being organized - project organization and the other things, tools, materials, also sets me apart and gives me an advantage over other workers who may have similar skills but don't have the pieces in place to push their business to the next tier.
I'm honest. I don't take on work I'm not comfortable with, and I make a point to demonstrate my confidence (or lack thereof) in my ability to do a project that they show me. Since my work is somewhat technical, this is like finding an "honest mechanic" - someone who won't screw you over. People don't want to refer their friends to people they don't trust. This only helps me. I've seen a lot of guys who just jump into projects without really knowing up from down. They might get the initial "bite", but eventually people don't want to work with them when they see the end results.
I don't mess around with debt. I have none and have plenty in savings. For the most part, I have the tools I need - that is my major investment. They will fail and be replaced over time - don't buy junk. Your "tools" might be different, but if you rely on it, get something that will work and work well.