Well, this is a question that was recently asked in another thread, and all I can say is, “it would take 5 threads on 5 topics just to give an overview”. The problem is there’s no one-shot change that fixes the game - you need to address the economy, the incentives to do activity X in sec level Y, how to balance personal destruction against ISK/resource gain (if my ships are getting blown up faster than I can afford them), but most of all, you need to give the new player experience a progression path that takes them from newbro to competing player, without losing 99.5% of them along the way.
The other problem is, CCP has made it clear that sweeping changes that require major new mechanics are not on the table - because they simply are not capable of coding such things any more without breaking the game. (See ‘new chat system’, see ‘most recent events’, see ‘Agency Agent Finder rewrite’) So any potential changes, to be realistic at all, need to be tweaks and rebalances of what we already have, or very simple additions.
As a one-off example, that needs a lot of context, I gave a reply in another thread:
That gives a notion of how you turn the current “throw people into the deep end of the pool, oh, and toss some sharks and piranha in too”, into a system of progressive dangers, rewards and challenges.