You get a few respec points as you go along that you can use to remove some points if you make mistakes, but not many.
To start, get an idea of what you want to do: Melee/Ranged/Totem/Curses/Minions/etc, then you have 6 classes with different characteristics (3 basic attributes and 3 hybrids), some better suited for each (eg witch for casters, templar for elementary dmg, ranger for bows), although you can play around. 3 types of defense too: armor (str), energy shield (int) and evasion (agi). With these preferences in mind, choose your class and plan your build.
Builds on the forum are always a good option for a first char, after a few levels as you get some more knowledge you can tweak it as you wish.
https://poebuilder.com/ comes in very handy for looking at builds, editing and planning.
Always get tons of hp and elementary resists, and you can always change your mind as you go along as long as you keep what you have already without too many changes. Early anything is viable. But later you will need a decent build.
Skills come in gems, which level up. You need to find them or get them at quests but then, you can use it. But as you lvl up, specialising into one or two attributes and gem types is recommended.