You will want to get some base endgame gear before you get into hardcore stuff. Depending on your current gear, Amdapor may be hard, same for wanderer's palace. Maybe start by farming castrum meridianum for some darklight gear, not necessarily full but the body and legs will help your defense a lot.

After that I recommend starting the relic quest, the process is long, so better start early.

After that, work on unlocking Amdapor Keep and running this for mythology tombstones, and do some ifrit hard to try and get an Ifrit's Battleaxe. Once you got that and some more darklight, you may tackle garuda.

I think this should keep you busy for a while...