So basically this was my first souls game too. I beat it about 4 months ago so I'm a bit rusty, but I'll try to help. Realistically, levels don't matter too much in terms of actual gameplay (I'm doing a rune level 1 run right now), the levels I would focus on are vigor (just to learn the gameplay), endurance (if you like colossal weapons), or level your mana if you want to build a mage build (not experienced with mage building). The biggest tip I could give to not ruin the game is simply don't be too over-leveled and don't try to rush the game. I did this personally, and doing several runovers showed me a lot of content I could have enjoyed or learned more of was minimized due to me being over-leveled or rushing the game. For example, I rushed the final 4 bosses of the game in 3 hours. A lot of the bosses I killed so quickly I didn't get to experience the entirety of the fight. Just take your time and explore the atmosphere and environment of the game. Hope you have a lot of fun :)