I just got my first Lapras... what should I do with it?

Nothing to do. Being nerfed, she would be under Blisseys and Vaporeons in gyms; and without Ice attacks, unable to use against Dragonites, and not a good Water choice because weak to Rhydon and Stone Edge Tyranitar or Golem.

Unfortunatedly it's just a water Pokemon with good water moves. It can be useful to prestige against Tyranitars, Rhydons etc. If you get one with ice moves, power it up to destroy Dragonites.

Ride her to Cinnabar Island duh....

Water Lapras is a good prestiger.
Keep it at this level and use to prestige against some Rhydons and Tyranitars. Be careful with Stone Edge, tho.

Be glad you got it now, I got mine before the Nerfs happened. It was my first buddy when buddys got introduced. It stayed my buddy for a few months.
Got it maxed out, then it got nerfed.
To low to live in gyms, to high to be a great prestiguer.
So sad.

Congrats! On,y have one myself. As stated above best as a preside mon.

At the moment leave as is. As has been said, it's a really good prestiger at that sort of level. I hatched one myself today, Water Gun/Ice Beam. Would much rather have had the double water moves like yours!

With Pokemon like Lapras, which is actually still a great defender and really only suffers now from low CP, I'm waiting to see what they do with the gym rework. I'm hoping they take CP out of the equation and give the likes of Lapras, Umbreon and Steelix the chance they deserve to shine.