The answer to that with POE is beautiful - any skill goes with any character, providing you build out your passive tree make it work. To plan a character, choose a skill gem you are interested in, look at what support gems may suit it, pay attention to the tags in the gem titles (spell, attack, projectile, elemental, lightning, minion, AOE, etc, etc, etc) and search out nodes on the skill tree with boosts to those, with the intent of building a path to stack them, while picking up mitigation nodes (life, armour, resist, energy shield) along the way.
Or look through the passive tree at all the interesting keystones (bigger nodes with more game changing effects, like my aforementioned Ancestral Bond, which means I can deploy more totems at the cost of not being able to do direct damage myself anymore), look at what skill and support gems may synergise with them and plan a path that picks up the keystones and other nodes that boost your gem’s tags.
There is no wrong way and believe me, if GGG’s Build of the Week series will teach you anything, people have come up with some crazy, amazing combos that even GGG never considered.
Sure, at some point you will hit a wall, typically either in DPS, or in survivability, but you will learn from it, or you can ask people how you could improve it, or what mistakes you made. Or you can plan it offline beforehand and ask for advice. Many times, gear will fill gaps, as opposed to D3 where gear makes the build.
Frankly any toon that makes it to mapping (level 60ish), I think has done alright and I don’t think that it is too difficult these days. Progression is so much smoother than it was in the early days. Back then getting many gems was very, very difficult, or near impossible for your class unless you rolled an alt to get the gem for you. These days they throw them at you like candy and make them all available at vendors, so you can plan a combo and know you will eventually have access to it.
I also have pretty much never traded, nor counted on a unique for a build, so keep that in mind, but in this game you can actually get a unique and get excited about trying to build a gem combo and passive tree around it.
I think the biggest mistake new players make is neglecting mitigation on the passive tree. Gear can make up some gaps, but you need to be picking up either life, energy shield or resist nodes (depending on your build). Ignoring them and stacking only the damage boosting stuff will eventually cause you some problems. So, plan a build using 60-70 points - never rely on that 93rd skill point to ‘make’ your build, because you may never get there. Even in softcore, dying has an XP penalty, so advancement is hard capped once you start dying too much. Look to plan a build you think is well balanced with around 60-70 points to ‘prove’ that your build has legs. From there you can spend additional points on filling gaps and rounding it out, or will at least have a feel for how the build is progressing.
And don’t forget resists. Always look to cap resists. Resists are very important. Gear, passives, who cares, get them maxed. If you do it on the tree, you are somewhat locked in, if you do it with gear, you have more freedom on the tree.