First, let it be known that this article isn't meant to force or pressure anyone into a polyamorous relationship or lifestyle nor is it meant to make polyamory seem more glamorous or better than monogamy. Both types of relationships take work, these are just some lessons I think most people learn when becoming poly.
1. One is enough
Usually the first reaction I get when people find out I enjoy the company of people of all genders and often at the same time goes along the lines of "Why so greedy?" or "Why can't one be enough?" What they don't understand is that one is enough but that one should be yourself. We are our own full people so we don't need to find our other half to complete us. My partners and I understand that our happiness comes from within us as an individual and we just choose to be happy with other people, not for or because of them.
2. Communication is key
Arguably the most important things in a relationship are communication and trust. Without these two things, relationships become unhealthy due to jealousy and lack of understanding. In many monogamous relationships, I've witnessed there is a lack of trust which leads to a desire to monitor and own one's partner instead of having a healthy conversation on the status of the relationship. Ideas like "I don't let my girlfriend talk to anyone else" or "If my boyfriend doesn't let me go through his phone he must be cheating" creates hostility in the relationship by invading on private and personal boundaries instead of talking about it. With my partners, everything is open and up for conversation. We clearly state what we desire and expect from the relationship, how we feel about our partners' actions and what we were going to do as a result of those actions. There is no need to wonder if someone is cheating or if their feelings have faded because they will announce important things like if they have a sexual attraction to someone else or have lost our sense of intimacy.
3. Humans are sexual and social beings
We need to understand that humans have certain desires and urges that aren't turned off because we enter a relationship. Now that isn't an excuse to just sex up every hot person you see behind your significant other's back and expect them not to be pissed when they find out, but realize that you will feel attraction to other people and it is best to communicate these feelings and decide with your partner what this means to relationship. Also, just because your partner has feelings for someone doesn't mean that they will act about those feelings or that you shouldn't trust them. If they have the self-control to tell you about those feelings, they have the self-control to not act upon those feelings.
4. Stop being greedy
I find it ironic when many of my monogamous friends call me greedy because I feel the same about them. Many people I know in monogamous relationships try to monopolize the time and affection of their significant other. It is perfectly fine and healthy to want to spend time with your partner, however, you don't have to spend all your time with your partner to have a good relationship nor are you owed constant attention. People have different families, friends and schedules so 12-hour phone calls and being attached at the hip is not a requirement of dating. You are in each others' lives not sharing one and trying to force your lives to be one can be suffocating.
5. Recognize when something is unhealthy or over
When you feel that you are meant to love one person it's really easy to feel like you should always stay and try to make things work but not every relationship is meant to last forever. You have to realize that you and your partner are capable of love outside of your current relationship so that you're together not because you feel that it's your only option for love but instead because you choose each other.
Understand that this is all based off my personal experience and that each person and relationship is unique and have their own wants and needs. These are just some ideas that I think would be healthy to implement into your monogamous relationships.