Is there a way to stop line memory? I have 12 pound mono on one of my rods and every time I cast it gets all twirly and makes it hard to reel back in! 

Kvd line and lure may help with that

x2 on KVD Line and Lure conditioner.

Or, go with braid for your mainline and tie on
a leader. Kiss line management issues Good
Bye!  

I've found that if I don't fish that often the amount of coils increased.

No line memory is one of the biggest reasons why I try to use braid as much as possible.

Gets twirly when you cast? Spinning reel? 12lb is pretty big for a spinning reel...

14 minutes ago, Kevin22 said:

Gets twirly when you cast? Spinning reel? 12lb is pretty big for a spinning reel...

My thought exactly.  OP is using a spinning reel.  Time for the Bait Monkey to show his face. 

Or go with braid as already suggested.

I am in the camp with switching your main line to braid, with a fluorocarbon or mono leader. You won't regret it.

How old is the line? Have you tried a line conditioner? Baitcaster, spinnning, or spincast? Was it spooled on reel origionally in correct direction? What brand line? 

Does your bail roller turn easily? If not, it could warp the line. Kinda like using the edge of scissors to curl ribbon. Usually twisted line comes off the spool in clumps when casting and/or wraps around the tip of the rod when line is slack.