whats the best way to get tomes

[Lavani]

I haven't done it yet, I'll take one for the team and tank wh$%re myself for a few 100k gil.

Lol, I've yet to see people offer money for that. But maybe you can find some poor deprived person to pay you :B. Also, you'd be surprised how often you get new players when you solo queue for the main scenario roulette. If it's the first of the day you get the tomes from run + the roulette bonus + new player bonus.

EX Roulette, High Level Roulette, Trial Roulette.
Then run a few extra dungeons. You'll cap in 3 days even if this is ALL you do.
Also yes helping people through old content such as t5 or the pre-shiva primals is a good way as well.
Also farm parties are a great way if they're actual farm parties and not a group of meatbags that managed to survive a single run and think they're good enough to farm. (I know that sounds elitist but really you should make sure you know exactly what you're doing before you join a FARM party)

You mean like joining a garuda ex farm party for the mount, and have all the dps kill the plume during tornadoes? Failing about 5 times and get two kills isn't a farm party?