Gems - Use them for scouts or LP refills (but the latter one ONLY in events (so you can get the 2nd/3rd SR)
When scouting, only do 50gem pulls, if possible
Here is a nice trick
Scout with friend points, if you do multiple or normal doesn't matter
Do it until you get an R
Then do the scout (this also applies to the ScoutingTicket)
The chances of an SR/UR rise
A friend of mine did it
Got 8R, 2SR and 1UR
Oh, and do the limited scouting (currently Printemps)
That guarantees an SR
I just did a 10+1
I'll from now on never scout via Honor Scouting
With the N's
First Idolize them (special practise)
Then use them in your team, to raise bond (do this once per different N, it's useless to do the same N over and over again)
Once it's bond is max (50 for I-N, 200 for I-R, 500 for I-SR and 1000 for I-UR) you get a side story
Play it, and get a lovegem (usually 4-5 lines on textlog), so quite short
Then feed them to your UR/SR
It's better if they are both the same attribute (Smile/Pure/Cool), as you get a bonus (20% extra EXP)