I saved up to buy my family season passes (just to let you know, I'm an underclassman in HS) for the first time in around 8 years. Took about 4 months of chores and mowing lawns. I hadn't been for a while and came back last year and got over all my fears of roller coasters because my dad forced me out of my comfort zone and had a total blast. Anyways, I am going to go 5-10 times this year, and want to know the best routes to ride the most coasters/thrill rides. (P.s. except Drop Zone, I hate Drop Towers)

What exactly are you asking?  Like...are you asking for a makeshift day plan on how the crowds  flow, or are you trying to ride as much in as little time as possible...?

If you want to avoid long waits, I would recommend getting to Diamondback during gold/platinum pass early rides, then Flight of Fear & Firehawk as soon as the park opens. (Diamondback is a popular ride that attracts long lines on crowded days, and Flight of Fear & Firehawk have relatively low rider capacities.)

 

Also, make sure to do some riding after dark. (The Beast at a minimum, Banshee, Diamondback, Vortex and/or Adventure Express if there is time.)

Buying Fast Lane would help immensely in this case as well if you go on a crowded day. 

^^ And Back Lot Stunt Coaster. 

Avoid Kings Island on Friday, Saturday, Sunday, and during the Holidays. Also if you get there by opening you will have a good portion of the park out of the way before the afternoon rush. Start your day at X-base and work your way out. If you plan on doing the water park, it's also best to the that first thing when it opens.

Well now, there are many routes you can take through KI that will give you different experiences depending out the route you take.  When you first come through the gates you'll have a decision to make: Right or Left.  My advice is to go right.  Walk a little bit then hang another right.  Go straight for a little bit then veer to the left.  Follow that path for a while then  hang another left.  Keep going straight and then make another left turn.  Follow this path straight until you come to a curve and then hang another right. 

 

I'd say as long as you keep following the main path and making right and left turns, you should be good to go.  Since most the rides are located on main paths, you shouldn't have any trouble getting to plenty of rides.  However, feel free to shake things up a bit.  Turn right instead of left and vice versa.  Maybe keep going straight instead of veering right or left.  The choice is yours and there are endless combinations of routes through the park! 

Lol, Ive been multiple times, I just want to know the most efficient way of getting the most rides in (such as when FoF is least packed, etc.)

Yep, Flight of Fear and Firehawk should be your first choice after the main park opens. If you walk quickly, you can get a couple rides on both of them before the lines are more than a few minutes long.

That's my other hint: if you are at a ride when the line is short, ride it multiple times.

After FoF I usually cut over to Beast with a stopover at Backlot Stunt Coaster. I like to hit Beast before Diamondback, because I've personally found I can't appreciate Beast as much if I ride DB first. So after a couple rides on Beast, on to Diamondback and if it is a weekday, usually can get in several rides before the line expands to more than a ten minute wait (usually around noon).

Banshee can be done at any time. It is my favorite purple people eater because its capacity is so high that even a longish line goes fast. And it is rare to find a longish line because it shuttles so many people through so fast.

If it's not one of the special days where middle school students take over the park, it is rare to see long lines for either Adventure Express or Racer, so those can be picked up at any time.