A good place to start
is being involved with respectful people. Respectful people take their partners feelings into consideration, and when they decide to do whatever they are going to do they are honest about it and honest about their intentions.
There is nothing you can do to help with jealousy issues if your partners are not considerate or your metamours are assholes, as in those cases it's often a matter of living in denial or the dark of don't ask don't tell. If you are that much in love with people whom it is going to be very difficult -- if not impossible -- to have a healthy poly relationship, yet you are adamant about seeing it through til it damages your relationship beyond repair, at the very least you need to be able to agree on safe sex practices so that you can realistically make smart decisions about your physical health in regards to diseases.
Some people are what is often referred to as veterans, and can deal quite well with the emotional hardships that most people face in polyamory. But you will want to avoid those who get into pissing contests about how "OK" they are with the most difficult aspects of non-monogamy. There are also those who had a real hard time themselves dealing with things like jealousy and every other obstacle that most be overcome, so they may not be very sympathetic to you having to deal with it.
And they are not wrong for not wanting to deal with your insecurities any more than is absolutely necessary. Some people subscribe to the theory that there are very minor things that your partners and metamours can do that will make a dramatic difference in your ability to deal with poly difficulties. But there too, there are some who firmly believe that doing so will only cause more trouble in the long run.
You need to find to out what works for you, but it doesn't sound like tough poly love is going to be the solution to your poly problems.