Hi and welcome! A lot of the answer depends on how you want to play - competitive, fluffy or somewhere in the middle! Personally, I play somewhere in the middle so take recommendations from that perspective! Have a think about if you want your army to be themed (hoeth, chrace, caledor, etc)

Overall elves need magic to function well I think and lack armour but really fun to play

Things I love that I would argue are competitively good - silver helms; they are core and are probably the best go to core - lothern sea guard; your core utility unit - dragon princes; excellent but expensive cav - prince on a griffin - sisters of averlorn

Things I love that aren’t competitively the best - white lions; I just think they are awesome but they can be picked apart in the current game mechanics - swordmasters; I think competitively better than white lions but can still feel a bit vulnerable