For night time visibility, a front light is critical and a rear light is good too. It's generally easier for drivers to judge your distance if you have solid lights, but flashing lights are more visible to peripheral vision, so I like to have both. Also, having a light with a physically large reflector or illuminated area helps with visibility. Notice how all car lights are a few inches by a few inches, or at least about 6 inches wide if it's a thin light bar. The tiny pinpoint LEDs on bike lights can be hard to see no matter how bright they are, and they make it hard to judge your distance compared to larger lights. You can get LED truck tail lights cheap online and wire them to a 12V source. In addition to light, reflectors on your clothing, helmet, and various places on your bike will help drivers judge your size, which helps them determine your speed and distance.
Using lights in the day is helpful, too. I have Reelights on my bike. They need no batteries and I don't need to switch them on, so they are perfect daytime running lights. They aren't bright enough alone for night use, but they add enough flashing in addition to my solid lights to make me more visible. The only downside is they are expensive.
I like my Alert Shirt vest for heavy traffic or at night. It's the most visible vest I could find, designed for construction workers around traffic over 55mph, but it's perfect for biking too. Note that the sizes run huge, and the "medium" is bigger than a normal men's medium T-shirt (it looks like it's equivalent to about a L or XL). The reflective material is good for a limited number of washings, so reflective clothing may need to be replaced periodically. 3M makes iron-on reflective tape you can put on clothes that don't have reflectors or refresh worn out reflectors, but I haven't tried it.
http://alertshirt.com/wiraja.htmlDOT conspicuity tape is good for adding reflectiveness to your bike or helmet, and you can sometimes find it cheap. It has strong adhesive, but it doesn't conform well to curved surfaces like bike tubes, so it might peel up. But it's really reflective and if you don't mind the edges peeling, it probably won't fall off completely. A single 18" strip was enough to get lots of coverage on my bike.
Tires with reflective sidewalls are good for adding more visibility, and they look like a bike to cars illuminating you from the side, which is good. When I'm driving at night and I see a bike, it often takes me some time to realize that it's a bike because it's hard to see the shape or outline in the dark.