Ok, so as I understand it, this is a new magazine, and you are looking at doing editing there. There is not much revenue, and you are new to the industry. This is tricky.
First, you need to understand what a contract is. Any lawyer will tell you that a contract is "an exchange of promises." You agree to do certain work and they agree to certain compensation. If you don't have both of these, you don't have a contract (I believe the standard I have seen in many states in the US is that compensation, or 'consideration' as it is called must be 'weightier than a peppercorn' which I think is a way of saying it must have some minimal materiality-- I cannot promise that my everliving soul will forever be yours if you do this work for me and have that be valid for example, or rather I can but it's not enough).
So you need to work out compensation arrangements during the contract negotiation process. This should include how much you expect to earn, when and how much they must pay you, and so forth. Since it is a new magazine you should try to be sensitive to their needs but make sure that you put yourself in an arrangement where if things go on slowly you aren't just doing a lot of free work with no expectation of future reward.
Now compensation need not all be financial. If you are just getting started, you could ask for something like 10 copies of each of the first few issues free of charge, with your role as editor prominently displayed. This would give you promotional materials to send out for other possible clients, so it would be a mistake to think that all compensation must be in the form of a check or a bank transfer. However, compensation is an integral part of all contracts whether incorporated by reference or spelled out. In your case you need to negotiate something that works for both of you.