Great ideas from all of our posters above. We do a lot of night boating, thousands of hours. You can get red cellophane, or "gels" to put over the gauges, or paint the bulbs with red nail polish. Although we have 3 red lights in the cabin, we do not have them on when underway. We do have several flashlights, which have dim red lights, as well as the bright white LED. If we have to locate something in the boat, we use the dim red flashlight.
Keep boat windows and back door open, so you can see, and hear any other boats. Do watch out specifically for small sailboats, canoes, kayaks, and even stand up paddle boards with no running lights. PWC--fair game!--most states they are illegal after sunset.
Chart plotter; Some have 'night vision" modes, with less color, and more in the reds. Keep the chart plotter as dim as you can.
Radar--since you are only going a mile or so--keep it on the range of 1/2 mile or 1/4 mile. BUT I doubt if radar will be of much help to you. I suspect that you are not skilled in both use, and adjustment (Radar is not at optimal, just by going on "auto tune". For each condition there is a best set of settings. (Gain, filters, Sea Clutter etc.) I agree with a cheap radar reflector in the "Rain Catch" position--Davis makes cheap, foil folding flat reflectors.
Wait until most of boats have left. We anchor, and have both our bright anchor light, and maybe a light in the cockpit--so our boat is very visible to other boats which may begin to leave early. You want all of these nuts, drunks, speed demons, etc to get off the water! Be sure that you know where the marina is by compass bearing--and get the boat headed in this way as you start the voyage back.
Spotlight. We do have a two power spotlight. We try and use it on "low", just to hit buoys, or rocks etc, when close. On occasion when another boat does not seem to see our boat, I have shined the light on the side of our boat. (Some folks are totally oblivious of other boats on the water!). If the spot light is used, it is only for an instant.
Navigation lights--be sure that they work and are bright. I like for my all around white light to be as bright as possible. I also want to be sure that there are no reflections off the foredeck or railings. (These tend to decrease your night vision). You can put the "pipe insulation foam over areas of the top of the bow railing if there is a lot of white light flare back. Some folks do put small shields to keep the white light downward. If you do this, be sure that your lights are well seen from even 20 feet away.
Other reflectors. I have white and red retroflective tape around the periphery of my radome. This will show up well with both white and red light and it does not take much light to make these visible. If one were to shine a white or red light on the boat, the radome shows up well.
We have had boaters follow us to our slip at our house--miles and miles from where they want to be--and as we dock, ask us where is XXXX marina. We have had to tell them to go back the way they came for 6 miles, turn right and go another 6 miles on bearing of XXX to their marina! Don't follow another boat--know where you are going!
We love night boating. You enjoy yours !