The people who you spend most of your time with, and who know you best, can be your best allies as a big part of your support system. A strong support system- comprising of family, friends, spouse, and co-workers is essential when battling mental illness.
Professionals and Peer Support Groups are also very important. The individual with a mental illness must like, respect, trust, and feel comfortable talking with all these people.

Family

Family can be tricky. In many cases, family members love each other, and have great relationships. If a member of the family has a mental illness, this individual is more likely to be treated with compassion and respect from their parents and siblings. There is a good  support system in place.
On the other hand, far too many families are much different. These relationships are toxic. They are like poison. A person already suffering from a mental illness could easily get much worse when exposed to this kind of environment. Far from a support system. Try to separate yourself from toxic family members.

As for my own family, my dad died before I got mentally ill. My mom was a huge factor. She supported me in many ways throughout all the years I was battling mental illness.
I have 4 older brothers. Every time I was hospitalized for full blown manic episodes (10 times), my mom and brothers were always right there with me. They always had my back, without any hesitation. I was  hospitalized for an average of 6 weeks. If feasible, my family visited me every day.
While I was in these psychiatric wards, this wasn’t the case for several of my comrades. They had no visitors, and appeared to be fighting their battle alone. No support system. Sad, but true.

Friends

You can’t choose your family, but you can choose your friends. Choose your friends carefully. Only associate yourself with loving, positive people who your psyche will benefit from.
Most people I thought were good friends left me when I became mentally ill. Looking back with that 20/20 vision, I realize that most of these people were just drinking buddies. We had a lot of fun together over the years, but they obviously didn’t have any compassion regarding the state of my mental health, and certainly weren’t there for me as a support system.
I still have a few friends from close to 40 years ago who have been loyal to me this whole time, and some more recent friends who are much more understanding and compassionate. These people are a part of my support system.

Most Importantly, Who You Marry !

As important as family and friends are, I think who you are married to is the most crucial aspect of having a good support system. By far, I spend most of my time with my wife, and she knows me, and understands me way better than anyone else ! My wife  (Elli) has a lot of experience working in mental health, which helps a lot. She is a natural care giver. She works full time as a home support nurse. She is a LPN (licensed practical nurse). It’s a huge benefit for me to have my own “private nurse”.

We have lived in a common law relationship for 25 years, and have known each other for 28 years. We have a lot of respect for each other and get along remarkably well. We haven’t had one argument this whole time !  Elli has been great for me in many ways.
At the same time, she’s completely supportive towards me being a stay at home writer. She always tells me that writing is my job. This includes blogging.
The bottom line is that Elli is the most important support person in my life.

Co-Workers

We also spend a lot of our time with our co-workers. Most people with a mental illness (es) are very sensitive. These types of relationships are extremely important to the individual.
I learned this lesson the hard way. I had a few jobs that I knew nothing about the people I would be working for, and with. I thought I could get along with almost anyone. This ended up being a disaster. Most of these individuals were very arrogant, which contributed to a very stressful work environment for me. So stressful, that it actually played a big part of me getting mentally ill in the first place.
Do your due diligence, and learn about your co-workers before you accept a job. The right co-workers can be a great support system. The wrong ones can create the opposite effect.

Peer Support Groups

Spending time with others who have similar mental health issues, can be very helpful. The peers have been in your shoes, and you understand each other. Peer support groups can be a very good support system.

Professionals

Psychiatrists and Psychologists can also be a part of a good support system.

* True support is revealed through consistent actions and a faithful presence.