One thing you need to remember is to ask people who look like they know what they are doing. Knowing when to ask for a spotter, isn't just safe, it's smart. Try to find someone who is doing a similar exercise and ask to working with them. Before you know it, people will be coming to you to be a spotter and of course it's only felt right to reciprocate. Sometimes people will rest in between their reps on the machine and then you can ask to work in. But don't take a fence if another gym member doesn't want you to do that. Think of the machine as their home or on a first cum first serve basis, they have the say.