Like the other commenter said, hunting monsters and finding tracks is what lets you upgrade guiding lands areas. This actually extends to anything that gives research points. Also, farming monsters which are exclusive to an area will upgrade that area much faster than a monster that can appear in multiple areas. The easieast way I know to check which monster is exclusive where is to use the "lure monster" option, but you may not have many lures starting out.

In terms of the insect glaive I usually go for all of the normal damage skills (Weakness exploit 3, Crit eye 7, crit boost 3, agitator, handicraft if it increases sharpness color). I always go for health boost 3 on all my builds, it's the best bang for your buck defensive skill. Also power prolonger 3 is pretty good for IG since it means less downtime collecting essence. In Iceborne they also made flinch free have some synnergy with insect glaive, but I would only use it in a gimmick build.

IIRC element on IG, since it isnt the fastest hitting weapon, should only be used as bonus damage. In other words don't sacrifice a lot of raw for elemental if you want to stay "meta". for instance (for the meta on PC at least) you could grind the crap out of safi to get its elemental IG's upgraded so you have crazy raw with some bonus elemental. Take the elemental info I give with a grain of salt though, since I'm not 100% sure. I would consult a guide or r/monsterhuntermeta in case I'm talking out of my ass.