What if i want to know how the effect of X card works? i need a guide for that

but yeah, i take my time to make my own decks and read the textament that the effect monsters have

Just generally have ash blossoms in your deck, forbidden droplets, solemn judgement and so long as you consistently get those in hand you'll be able to avoid most OTKs. There will always be a rare chance a person gets that PERFECT draw for his gimmicky one-trick OTK, but other than that you will almost guaranteed survive more than 2 turns.

As for building your own deck, just make sure you can guarantee you can get the cards you want to have in your hand. Spend a good amount of time building your deck while accounting for decks you had experience fighting against and it'll go really good.
If you have a friend who plays the game, doing private matches vs them would be good to iron out your deck, so long as you both improve your decks over-time.

i mean, i don't know if my deck is bad enough when i keep losing in the first turn without even playing

Finally a guide that makes sense!

I enjoy the Deck I built when I first got on the game, cause I couldn't find the packs for the Deck I wanted, though it was after I learned you could craft to get the packs. but I win vs most Deck types if I get the RNG. But those top end decks just absolutely counter and clap my cheeks lol.

Agreed. I hate competitive YGO, but the truth is, if you play for rank and victory, you make your deck as unfair as possible

if you win you don't build your deck to be fair

Uh, not all decks need to suck or players need to be bad to lose. There is a thing called broken decks, and there's quite a few of them that are leagues above others.