No One Can Help You
Many people will disagree with me on this one, and may have had different experiences than me. However, I expect it's served me well.
Networking
Publication could certainly come from knowing the right people, building a network, marketing, or seizing opportunities. However, mine came from endless hours of playtesting, introspection, and detailed work, which led to a very good game. Then, I just emailed a publisher, and they published my game.
If you're serious, you need to stop thinking about publication. If you make a great game, it will automatically pass that hurdle, and be published by someone. Then, it will become a hit.
Community
Yes, playtester feedback is great, and playing other games and prototypes is instructive. But, beyond that, I don't interact with anyone. I don't participate in communities, contests, or conventions. (I do participate in the Radlands community, but it doesn't help me in any way.) I don't think these things are necessary, unless you're planning a Kickstarter slog, which you shouldn't be.
Many people will say that they benefited greatly from interacting with a community. But, among the actual top designers, how much would they say their hit game was their own work (and that of their playtesters), and how much was thanks to a wider community?
If you need playtesters, a community can be a great place to start. Eventually, you want a more efficient source of playtesters though, like a playtest buddy, and eventually, volunteers.
If you're benefiting from a community, you're probably not a great game designer. Or, you're new, and they're teaching you the basics. If you find a community that really does contain top designers, which you probably won't, you've struck gold.
If you're just designing for fun, a community might be a great idea. Work with other people, and have a great time.
No one in the community is going to be successful, except for a very, very small number of people, and they can succeed without the community. We can't all win.
There is no help
No one can help you, and you cannot help anyone else.
If you want to be a really successful designer, other people cannot help you. They can be your playtesters, and make your life easier, but they can't take you to success.
You cannot help others. They must gain their own insights, that surpass those of others.
You're learning from me right now, but anyone can do that, so you'll need to add your own insights and expertise. What I'm doing here is really lifting the tide for all boats. If my advice made everyone twice as good, there would still only be 5,000 board games published next year. That's great for gamers, but it wouldn't help designers.
You either have the ability, attitude, work ethic, and luck, or you don't. None of those are things that can be given to you by someone else.
There is no shortcut to making a great game, which is the only way to succeed.
I've personally helped multiple people go from being woeful designers to competent ones. However, neither of those levels of competency yield publication or any other reward. They did become better playtesters for my successful projects though, and they felt better about themselves.
If you're designing for fun, you've already succeeded. If you're designing for success, and you get incidental fun out of that, you've also succeeded. If you've gone well beyond that, and put serious, non-fun work into a game, you've probably made a mistake. Obviously, if you get to publication (especially somewhat-successful publication, then it might've been very worthwhile.)
Work alone
I have playtesters, who give me feedback, and sometimes advice, but they're helpers, not co-designers. I have publishers, who I work with. Beyond that, I don't work with anyone.
If you're learning from others, you're not ahead of them, and therefore you're not that great.
If you're co-designing, there's almost zero chance that you're both great. The one of you who is better should just design by themselves, or enlist the other as a subordinate helper.
You should be mostly working on your own.
An analogous story is that I do very well on the stock market, which is something very, very few people can do. I have my own insights and philosophy. They didn't come from anyone else. They could not have come from anyone else, or they would not be better than 99% of other people's insights.
If you want to be great, it's not something that anyone else is going to be able to teach you.