I don't know your exact situation but some possible routes to take can be;

Set up a neighborhood watch

Get training for everyone involved in the watch on how to properly handle crises, high stressful situations and potentially people that are armed. Crisis management classes are offered to civilians and it can be useful to understand how to approach delicate situations and use nonviolence to resolve an issue.

Learn self defense techniques such as Brazilian jiu-jitsu. BJJ is pretty good because you can disarm your opponent with out having them hurt themselves or anyone else, basically you just make your own body into a cage and they can't escape and eventually tire themselves out.

Work out in addition to learning self defense techniques, be stronger and be able to run for long distances. In case the issue ever arrises your body can handle stress and you can be more of a formidable force.

Potentially learn how to use firearms, not necessarily as a deterrent but if somehow you come in the possession of one (some criminal drops his gun for example) you can understand how to safely disarm it. Also if for some reason the time does come to use firearms you will know how to do the basics.

Get an EMT-B license at your local community college. In case anyone gets hurt you can administer life saving aid quickly.

Also maybe get radios for the rest of the neighborhood watch and have rotating shifts. You don't need patrols but just people looking out for any weird occurrences.

Also understand that you don't want to do vigilante justice, you want to ensure the security of your residents and even the security and wellbeing for a trespasser/assailant/etc. Lethal force has to be the absolute line of defense and you have to be mentally prepared that if you're going to go around doing neighborhood watch you might have to kill someone in order to save others.

Generally from my understanding the most common crimes are vandalism and theft. Generally these people are unarmed and don't mean to physically hurt anyone. Approaching these situations armed can escalate them, generally if life safety is your top priority (which it should be) speaking directly, calm and firm can settle these situations. However I do not recommend engaging in these situations without any proper training.

Ironically enough your police department may even offer free classes on how to handle: suicidal people, belligerent people, home invaders, etc.

If someone is attacked and you have the ability to administer any sort of aid that is relevant to the situation, you are legally required to. Also note that if a patient dies in your arms you have legal protections under "Good Samaritan Laws", so long as you administered the proper treatment to the best of your ability from your training. Do not say you know CPR but actually don't, that is the worst thing you can do and can potentially kill someone. Only step in if you have proper licensing and training to do this.

I worked as a firefighter not as a police officer or anything, but what I can tell you is that training is everything if you really want to do what the police are suppose to do. Even the police sometimes are not properly trained and bad things happen, you need all relevant training you can get, along with any neighbors that decide to do this as well.

Your ultimate goal should be life safety for everyone, if a victim wants to press charges using the police you should not stand in their way. If you really do not trust the police to safely transport the accused, get the accused' name, name of the officer's and badge numbers, license plates of the transporter, and ask if you can follow them to the holding cell to ensure for his/her family that he/she made it there safely.

You can also have body cameras installed on all of the watchmen involved. In case of any legal ramifications you can have evidence to support you, also incase the police do something bad to a suspect you can have evidence of it as well. However you need to establish a guideline on how to release the footage and when to.

For instance some people displayed on the footage may not want it to be released, you have to respect their wishes. But sometimes if you don't release the footage that could cause something worse. That's why you must have rules and regulations on how to approach situations within the scope of everyone's training.

Also most importantly understand the laws of your area and make sure you're following the rules legally. You may be fine being sent to jail for something, but your neighbors shouldn't suffer life in prison because while you felt something was the moral thing to do, it was actually illegal and now because of how everyone was trained they may actually be sent to prison. So make sure that won't happen.

Remember you're a neighborhood watch, not the army, not the police, or anything. All you can do is observe and report. You can talk to the suspects and administer aid and defend yourselves, but you are legally limited in your abilities. So make sure you can do the mortally right things while also operating within the law, also you need to self regulate your group so designing rules and regulations are good from a legal standpoint to show you're not a bunch of jackasses running around with M14s, but people who want to help and ensure security for all parties involved, even and especially suspects.