There aren't many combos for elise but here they are.

GAnk combo 1: Human E > Human W > Human Q > Spider Form R > Auto once > Reset auto with Spider W > Spider Q

Gank combo 2: Spider E > Human form R > Human E > Human W >Human Q

Hiding in bush Combo : Human W > Human Q > Human E > Spider R > Auto attack > Reset auto Spider W > Spider Q

What is strong about elise is her dives, snowballing, and ganks.
WIth elise you don't just want to do regular ganks, you want to dive the enemy at their tower and rappel out! This is what makes the champion a great early game champion. If you aren't diving, you are not playing elise right.

Other quick tips is using your spiders to do Dragons and jungle camps. Let them tank the damage and you will be healthy while soloing objectives!

Ruinic Echoes first, RED smite 90% of the time unless they have hard to gank champions. (If you are snowballing early get a dark seal, so you can think about upgrading to mejais later)

After that go sorc boots almost ALWAYS unless they are all ad.

Then go oblivion orb (IF NO MAGIC RESIST) (DO NOT UPGRADE TO MORELLOS UNLESS THEY HAVE LOTS OF HEALING)

If they have magic resist, instead go haunting guise into liandrys.

Then I go zhonyas in most cases 3rd item unless they have lots of ap threats, then you can go banshees.

If they have lots of magic resist go 4th item Void Staff, if not, go Rabadons.

There are two ways to gank as elise.

1. walk up in human form and land cacoon (most cases)

2. Spider form rappel towards them and switch to human form then cacoon. (Uses your safety ability [rappel] as an engage, so make sure when doing this you are sure the enemy will die)

Be sure to be patient with cacoon and know if they have their mobility spells up.

This champion is pretty fun when ahead. You one shot almost all squishies and because you have percent health damage on your Q ability. You also do good damage to tanks becuase of the same reason, but be sure to get void staff when they have magic resist because you will have a hard time being useful.

Anyways, if you are ahead, invade the enemy jungle and one shot him OR just keep diving enemy champions, you won't even have to land your stun because of your damage.

Other things I do later into the game is just hide in the enemy jungle bush and one shot whoever comes by, usually when objectives are coming up or enemy red/blue buff.

When I am behind as Elise I am often able to come back, the reason is that you have to just bush camp. You need to farm or find gold on the map until you have the ruinic echoes, sorc boots, oblivion orb combo. Once you have those items, even if you are behind you can look for a one shot on the enemy squishies.

So basically, when behind get those core items, and then look for picks or flash cacoon on a squishy target!

You are a decent champion at this point in the game as long as you arent too behind. Just do your job, look for flash cacoons on squishys, or if they don't have magic resist you can cacoon a high hp target and chunk him for an upcoming fight or objective. Make sure to know that your human W actually does decent poke! So utilize that. Sitting in bushes is good too! Abuse the enemy lack of vision!

If you are behind, you will be useless. If you are even or ahead you are basically playing like an assasin. Again, you are flash cacoon reliant unless the enemy mispositions or doesn't have magic resist. I've had plenty of late game elise games where the enemy doesn't build magic resist and I can 1v9 even as a single target champion. Just have the mindset of an assasin and you will be fine.

Death Blossom is the cleanest skin, and IMO the only skin where her spider form isn't ugly, cause lets be honest spiders are ugly. Otherwise I think bloodmoon is my secondary option, the human form looks nice, as well as the animation for cacoon/human W.

If you want fancy animations you can go super galaxy elise (my third option if anything), but I only go death blossom.