Planning on having a god or godess of trickery be the bbeg of the campaign and was looking for tips to help keep the game entertaining.

First of all, the enemy is literally a God. You can't have your players simply fight it (well you can, but I wouldn't recommend it). I'd say have them try to find something that can destroy, seal, or weaken the God while said God tries to stop them. Also make sure to do some trolling. Make the players really hate this trickster Deity by having them outsmart the players time and time again till the players can overcome it in a game of wits. Just my suggestions

Trickster god? Pull a Loki and have them shapeshift. Maybe they spy on the party as the pet owl for a while, maybe they are secretly that NPC everyone loves. You can't do this all the time or it'll get old and the players will become cynical. Do it a little bit, in arcs that are significant, and you can make some interesting moments happen.

I think a trickery deity would keep their real motivations close to the vest and let the party go wild with conspiracies and misinterpretations. An evil trickster might manipulate the party into doing their dirty work for them. A chaotic trickster might not have any real goal other than causing mayhem. Figure out what the god wants and how the party could be useful or stand in the way, then have them act accordingly. 

As for the campaign climax, it's off-brand for a deity that thrives on craftiness and deceit would be keen to allow a head-on fight, so maybe introduce a problem to your players about how to pin down said deity. Maybe they need to summon an avatar of the god and trap it in a mystical jar. Maybe they need to infiltrate the divine realms somehow and sneak attack the trickster on their own turf. Maybe they need to lure the god and turn them mortal with a legendary potion. Or maybe they need to steal the god's power and divine portfolio for themselves from the depths of the Celestial Vault. Idk. Give them some ideas and then let them be creative. That's a great way to keep players engaged, too.

The problem with your BBEG concept is "If the BBEG is actually a god, then the characters have no way to be successful." ... unless you develop a plot line and explain why this god isn't all powerful, all knowing, and capable of simply altering reality as they wish so that whatever they want to have happen, happens. That is the nature of actually being a "diety".

Rime of the Frost Maiden has a weakened avatar of the goddess Auril. She is expending so much of her power preventing the sun from ever rising in the frigid north that the avatar that is present on the prime material plane is much weaker than the actual goddess would be. The characters can defeat the avatar, returning Auril to her native plane and ending the endless winter at least temporarily, but there is no permanent "victory".

So, if you have a trickster goddess as your BBEG ... what is constraining her actions? Does she have a bet with another god that she can manipulate events to turn out the way she wants without using her divine powers ... except manipulating the information available to gullible mortals so that they choose to take the actions she desires? Do the gods of your world have a pact that they won't use divine powers directly on the prime material plane? They can only act through agents and influence.

Once you know the limits on the god or goddess' power on the prime material plane, you can start coming up with the plot line ... what do they want to achieve, why, how do they reach that goal? Perhaps one goal is that she wants her followers to become more powerful and gain more influence ... to do that, her opposition needs to be eliminated so by supplying the party with information about an evil cult, the party can be convinced to destroy those in the way of her followers. Similarly, perhaps she finds the thieves guild to be a threat because it has subverted too many nobles. So she gets the party to fight the thieves guild, ideally wiping it out, while her agents take over control of the subverted nobles and city officials.

Anyway, just some things to think about ...

I like my gods to be distant an unknowable. I really like the 5e model of not even giving them stat blocks.

So really to answer the OP, I wouldn’t have the PCs fight a god — they’d lose. But they might be able to overturn a god’s plan, or a god’s desire.

If it were my campaign, I’d focus on that. The god wants to do X. The PCs want to stop them. That’s the kind of thing other gods might be on board for. Then the PCs have potential allies. But gods, generally, won’t be cool with mortals killing another god; they don’t want anyone getting ideas.

You have two options here:

1 - Gods in your world aren't literal gods, and instead are just beings with a superior grasp of magic/technology. This can be underwhelming especially if you have clerics/paladins in your party who go heavy on dedication to their deity of choice.

2 - Gods are literal gods and as a result are unkillable. In that case you can have the players fight the acolytes of such a god, you can have the players fight avatar or scions of a god, but a literal fight with a god is sort of outside the scope of the 5e. 5e overpowers players to such an extent that working within the mechanics provided you'll never create a satisfying fight with a god. 

My own previous campaign created a world where the gods are beings who utilise natural sources of magics to create worlds and seed populations. They are beings who are naturally a part of the weave of magics. They can never be killed, but they can be severed from the weave. Doing so has disasterous consequences however. If a 'god' is severed from the weave, then magics begin to weaken and eventually recede from the world. So in this world there were 6 'gods', that means if one god was severed from the weave, 1/6th of all magics and spells just end. I literally took all abilities and spells and split them evenly between the 6 'gods' of this world. They are no longer castable. In terms of game balance this makes any encounter with a scion of the gods much more balanced, much more difficult in short. In the two campaigns I ran in this setting, both groups managed to prevent rituals to sever a god from the weave. As such no spells are ineffective.

The thrust of the campaign was that the party were set out on a path that would safeguard the world's gods by recovering the 'avatars', items which the gods used to create the world. The ostensible big bad was a society that wanted magic and the gods ended. The party struggled agaisnt this society, but eventually came face to face with scions of the gods. It was here, that they found out that the gods intended to destroy all sapient beings in the world - thus protecting themselves from any future attempts to destroy the gods. The parties who encountered this obviously decided that this was a bad idea and tried to 'fight' the gods. This of course was impossible, so I presented them with the scion of the gods. A titan who was immune to its god's abilities & spells. Defeating this scion would basically cause the gods to leave the world and leave it to decay and wither without their influence to maintain the world's weave. The choice then for the party became to drink from the source of the weave and effectively take on the task of becoming versions of the gods themselves, or to allow the world to darken, wither, and die. 

The scion fights were - anti-climactic. Now, I acknowledge that part of this could easily be my own DM style not being competent enough to pull off the ideas I have, but even so...it wasn't great. The campaign to be clear I feel like worked well. It was the twist/sting in the tail that didn't work very well. 

So my advice - don't ever let the party actually fight the god. In future I would take the 'Stargate' approach. The ascended ancients in that world self-regulate. They basically ensure that these higher beings don't ever directly alter the natural course of mortal events. So, I would have an evil god be operating beyond the notice of the other gods, and have the party fight against acolytes and find a way to contact the other gods in order to encourage them to punish/stop the evil god. 

I think all depends on what the gods in your setting look like, and what their position is. A lot depends on that.

I generally would advise on having smaller goals, smaller adventures that connect to the big problem/adventure. It's good  for your players to feel like heros if they have accomplishments that feel like accomplishments, like they actually made a difference. It's also better for them to remember things. Don't forget, you got all the pieces of the plot, all looks logical to you. Your players don't have that benefit.

Otherwise any tips would have to be made in a long talk about the exact situation in your game, and what you and your players want ^^

I have a boss in the works along these lines. basically theyre a god of destruction and have basically stopped being a god altogether, instead becoming a godlike monster on par with the turrasque