When to step away from guides

No problem, that's what a lot of us are here for.

Do you mind if i add you on steam

Sure go ahead, you won't see much of me on it though. Right now I've just finished up playing the end of season 3 for League of Legends, and am avidly playing Smite. It should be about a week or two until I play Dota2 often.

Almost every build for every hero has a bread and butter build that you follow until maybe.. level 3 and depending on what you require you'll level up accordingly and buy items according to your current situation and how the future may be for you.

I have a friend who off lanes with timbersaw and he doesn't get much farm, so be basically goes full sustain to get exp and try to last hit with auto attacks or skills since he does pure damage. He maxs out the grapple after the reactive armor and adding one point into the whirling death. It's proven to work for him but hes not as viable early game. Once he reaches about maybe level 12-16 theres a curve in his gameplay since hes able to dish our some damage and help in team battles. But say if you're playing middle and you're going to gank, you would probably max our the hook then the whirling death since you'd want to be able to spam your hook as much as possible to get closer to the target.

TL;DR it all really depends on what lane you want to go to and the hero match up for that lane. You kind of essentially already know whos going where when you understand the fundamentals of each hero.

This is what happened to me. I started to see things like "this character needs a lot of agility" or "this character does really well with a disable item".

The harder thing to learn, which really has to be trial and error, is something like "this guy has no armor, so even though he has 1800 HP he is still squishy" or something like that.

Usually you can tell that if you have a right clicker, you want to go for damage and/or attack speed.
If you have a nuker, you want mana regen and probably some armor / hp boosts.
If you have a support, you want Mekansm and wards
If you have a slow melee hero, think about Orb of Venom early
If you are squishy and have high damage and/or attack speed, you probably want lifesteal.

As far as order of abilities, you usually want to get a damaging active ability at level 1 (usually, not 100% of the time). I usually like to max out passives first, but honestly every hero is different.

Play a few Single Draft games and force yourself to learn new heroes.