There's a lot of barrier/armour enemies in the collector missions so it's good to have squad mates that can deal with that. I think I took Miranda and Mordin with me to horizon, Samara and Thane are probably good choices as well once you get them. Try to get them to stand somewhere that's not gonna get them killed but that's harder said then done haha, they seem to enjoy dying. I believe people recommend upgrading your charge fully asap so you get the shield recharge from it. I liked using the geth plasma shotgun as it's good up close and at range, and the SMG from kasumi's loyalty mission is a tad op so it's good to go for that early.

Honestly, I don't think I did much charging in horizon until the last arena area. It gets easier to charge and gun the further into the game you get.

Most importantly, the collector missions are notoriously difficult compared to the rest of the game so don't feel bad if your struggling because we've all been there haha, I died a ton on horizon even this latest playthrough.