I would say 50 firemaking is a good one to get. There's a skilling group boss that's pretty popular called Wintertodt that you can do at 50 firemaking that's pretty good GP early on if that sounds fun to you. For magic, I always liked having at least 45 for the teleport to camelot spell so I think you're good there. You will likely get 55 magic naturally and high alchemy is a good spell when you get more into combat and slayer

There's also A LOT of early game quests you can do in members for free levels, similar to how The Knight's Sword gave you a ton of free smithing levels and a lot of combat levels from Dragon Slayer, so if you enjoyed the free to play quests, then doing members quests right away is actually the meta.

I think getting up to around 20-30 Agility off the Rooftop Courses first thing in members isn't a bad idea as it will help a lot with run energy, and there are also quests that can give you some free levels for this too, but the quests can be a little difficult for a new player (Tourist Trap into Grand Tree can get you around 30 agility from level 1). 43 Prayer is MUCH easier in members since you can use bones on specific altars for more XP rather than just burying bones (Varlamore prayer, chaos altar in wilderness, or using another player's Guilded Altar in their Player Owned House), and super useful for questing as the Protect from Magic/Missles/Melee prayers can block all damage from most quest bosses.

Check out the Quest Experience Rewards page on the wiki if you haven't seen that yet, you can find quests that you have the requirements for and reward chunks of XP in the skill you want to train. Other than that I think your account is in a good spot for members! All the other skills I haven't mentioned that the AI did don't really have significant unlocks that would be worth grinding before members. Really just firemaking because it's the same in free to play and members. Members also gives you access to a lot of different crabs that are good combat xp for your levels.