im thinking about playing ranked should i or should i not

I think you should as soon as the new season starts. I spent about a year just spamming normals trying to "get good" before i played ranked, but honestly the only way to learn to become a better player is to play games that actually mean something. You very likely won't start of very good but trust me after about 100 games the ranked anxiety goes away and you can really reach your potential. Hope this helps! Good luck dude.

If you have at least 20+ champions, are at least some what decent and understand each role, but are at least confident in 2 roles with at least 2-3 champions in each of those 2 roles then it's alright.

Though if you haven't started ranked yet, I'd prob wait until the next season since this one is ending in about a month anyways.

Are you new (less than 6 months experience?) If so, dont. You will just drop like a rock to bronze V and remain there for eternity.

I suggest you wait until you have at least 3 champions (at least 2 for per role, 2 roles) that you are very good at (60% or higher win rate). You will also need full rune pages for them (for a mage, vs AD and vs AP sets, for example), and a good understanding of counterpicks and team synergy.

Picking a champion you know really well is always the best choice you can make, even if it is into a bad lane matchup. Having champions that cover eachother's counters is helpful, as well.

More importantly, dont take it seriously. Remember the rewards are basically meaningless, it is all for fun. Ignore trolls, flamers and lifeless ragebabies, and other SRSBSNS bullshit.