Build:
Level 1 - Always Naishas. You can solo the hard camp at level 1 with this pretty easily. Just use it to macro pressure the enemy team all the time. It’s also really good in teamfights and easy to reset it.
Level 4 - Always Blade Dance. It is really good to clear waves/camps, it does pretty good damage, it gets the buff from the level 16 Armored Assault and it is usually better than Pin Down unless the enemy is really bad and keep helping you get those Qs.
Level 7 - Elune’s Wrath. Extra burst on your Qs. If you are good at hitting them this does really good damage.
Level 10 - Almost always Cage. Even if you don’t have big tools to combo with it, it’s nice to just help your Q resets in general and to keep people in the place you want. Disc is good if you really need to isolate one target like Diablo with LB. Use it on him, disengage, engage after LB ended.
Level 13 - Bladed Armor. If you are still learning her, Shadow Armor is also good if you are not used to getting those Q resets all the time.
Level 16 - Armored Assault. This is a major talent for her. It boosts your damage so much (even Blade Dance AND Naishas). If you can get those Q resets + AA in a fight this will deal A LOT of damage.
Level 20 - Shadow Strike is usually the pick to kill one target. Huntress can also be good.
There are some players who like to go W build or even E build, but that’s just really specific to them. It’s like the W build on zeratul. You usually don’t draft Zeratul for the W build, as you usually don’t draft Maiev for the W/E build. Also the build I shared above is what people use at the high levels and it is the build that synergizes the most with her playstyle and why she is drafted.
What you want with her is generally just macro early game. Soak and do camps with Naishas and you already got some pretty good pressure on the map. In fights, you can either hide somewhere and try to walk at the enemy to get a good W/ult, but practice the engage with E + W/Ult as well, because it’s really good. Make sure you don’t waste your trait on low damage abilities, but also don’t hold it too much, it’s kinda short cooldown.
What helped me a little bit was going into try mode and just practice her abilities against the target dummies. Try every combination, engaging with E + W, Ult, Q resets… It really helps.
Hope I could help a little bit.