Do not use a smaller tip than the ferrule
You drasticly increase the chance of ripping the cloth on screw shots as the edge of the ferrule will be exposed and can catch the cloth. Playing rail shots can leave some nasty marks as well.
My recommendation is to always use a tip 1 or even 2 mm larger than the ferrule. Sand the ferrule top and the bottom of the tip, apply your glue to both surfaces, push the tip on wiping away excess glue from the ferrule.
With the larger tip it's easier to apply, you get lots of room for shaping and you've no chance of damage.
The feel of a tip is everything, my preference is one that's firm. I actually like the ElkMaster blue tips but like everything that's mass produced the quality varies a lot. I pick through for one that's thick enough that it'll survive some compression and fairly firm. Out of a box I might find only 10% that I'd use
Because the tip is firm but not a rock, there's bound to be some compression when I initially start playing with it requiring that I reshape it while I play for the next while. By using a thicker tip you have the room to reshape and still have a proper, playable tip at the end instead of a tip that'll be done with 30 hrs play.
If I find a tip I like but it's not quite firm enough I've used a vice to compress the tip before applying it. Saves you the trouble of winding up with a tip that's too thin after you've hit a few hundred shots.
I'm not a huge fan of crazy glue, it makes putting the tip on a rushed process and it's almost impossible to clean off any excess. That's just me though, lots of people use it and have no issues. Personally I've always liked Tweetens but hey, I'm a traditionalist and don't need everything done fast
Go big with the tip, give yourself the freedom to truly get your tip hitting the way you want. It's a process and takes a few sessions but the end result is a lasting tip that generates the spin and feel you want.