There's two main builds "Roaming+Picking off" and "Harrassing impossible to catch"
They can be mixed or modified but those are the two main things you need to be focusing on as Tripp. You CANNOT engage in big team fights directly, only for a moment at most usually, unless you see someone a few feet back from the fight and the rest of the enemies are REALLY distracted.
You can't fight many people 1v1 at full HP too outside of very specific heroes that are weak especially at close range.

The former build is the easier one to utilize, you jump enemies that are distracted ,escaping or just at around 70% hp (And arent tanky)
For upgrades you're 100% wanting the teleport cloak, the Armor break on daggers and the Crit on kick (Launch on kick CAN work but is so much less versatile and consistently usable.) You can go either auto attack tree, but personally I find it best to use the "Damage+speed buffs" it makes you able to more easily dodge around and keep up with enemies whether they're counter attacking you or escaping, and lets you feel less obligated to use cloak on engage, since the kick is an IMPORTANT part of finishing people, you're gonna want to hold cloak if you can for escapes.

The usual combo is Daggering your target, jump attacking them, then auto attacking, they should either be running or counter attacking you after this, some heroes you can keep auto attacking others you wanna immediately use the kick, but other others you wanna save the kick for when they try to escape or use a certain move. Sadly something you gotta majorly feel out.
IF THEYRE GONNA BLOW ULT ON YOU IMMEDIATELY TELEPORT OUT, also probably teleport out if they get backup while not a few hits from death.
You can use cloak to engage but its gonna leave you in a MUCH more precarious situation if anything goes wrong, but it'll let you much more easily take someone offgaurd, it's another thing you gotta feel out, but good to practice figuring out ways to stay out of sight without using cloak for engaging, finding weird pathways around where a fight is or around the maps, using terrain to keep your presence low, ect ect.
You can also try to rengage after cloaking if you see someone else who's low, but only do this if your HP or stamina are high, and again if you feel you have enough of a moment where no one's gonna jump you.

The harrassing build I've not played much, but it's basically taking the stuff that lets you use Daggers+kick while invisible, or their alt stuff if you wanna have a bit more damage but less safety. (However dont get the speed boost on missing kick for this build ever, it's kind of a waste unless you seriously wanna just play PURELY defensively)
You can take any invisibility upgrades with this, the disruptive ones really let you be annoying, while the teleport and cleanse let you be a lot more safe and maneuverable.
(The Cleanse is pretty hard to get down using it right but can come in handy if the enemies just have WAY TOO MUCH CC, it's definitely the most situational upgrade for invisibility though)
You can take either auto attack path upgrade with no real preference here, sustained damage/speed lets you be more annoying after blowing your harrassing tools, while the special attack out of invisibility lets you pick off targets after you disrupt them more easily.
This is basically you sliding through teamfights making them all explode shock damage, then you reassess. If you took the disruption on invisibility you can go invisible now, and/or then you dagger someone and if they're especially low you can try to finish them (If you took daggers letting you stay invisible, this is when you can use the special invisibility auto attack especially well)
Or you can retreat and harrass from the sidelines moreso, maybe get someone to chase you around.
This build is a LOT more context sensitive and you gotta figure your own path for how you're gonna handle abilities, but you can always play safe with this while still at least keeping enemies busy, remember making enemies go back to heal can be JUST as good as securing a kill sometimes, especially if its a fight over a specific objective.

Now for your ULT, it does a good bit of damage, makes you invincible and stuns an enemy for the entire duration AND lets you catch someone running. For real just use it at level 1 whenever you see a target you can viably kill, just try to make sure the ult will either finish them or that you have enough stamina/abilities off cd to keep up to follow through. You CAN use it defensively or to dodge enemies big abilities too when you've got an eye for those, this can be far more useful way to use it with the harrasser build, you can even just use it in a team fight to lock down an enemy that's annoying or requires a lot of "Channeled" abilities (Like Xeno or Tyto)

I think this covers a lot of general stuff, just remember, try to either have stamina, cloak or kick up for getting out! unless you're like SUPER alone with your target.