Well, I don't think anyone is really sure just how exactly time travel can mess with stuff. I would probably take a page from some time travel movie I saw. I would want to avoid any sort of temporal paradox and avoid too many changes.

So, I would probably remove myself from the equation as much as possible. Go to a hotel or somewhere where I can avoid accidentally running into anyone I might know. Leave all electronics behind, but take a book or something. Spend the whole day avoiding TV/News/People and just reading or work on perfecting a skill. At the end of the day I would call up a broker from the hotel room and find out which stock had the greatest percentage gain that day. Just enough information for one good trade.

Then I would go back to that morning, buy up a ton of that stock, live out life normally, then sell the stock at the end of the day.

Rinse and repeat for a short time.

I would absolutely avoid something like winning the lottery, but for those of you who would use time travel to win the lottery, you might want to follow the advice from this comment here: https://old.reddit.com/r/AskReddit/comments/24vo34/whats_the_happiest_5word_sentence_you_could_hear/chb38xf/

Maybe go back in time and punch my dad in the balls about 9 months before I was born.

Then all that would remain of me would be a weird story where my dad got socked in the nuts by a ghost that looked just like him.

My own birth, I guess.

Have you learned nothing from science fiction stories? I would not change anything.

I'd tell my younger self to stop fuckin carving "Operator symbols" into furniture. And also to get into playing minecraft...

I would install an automated missile system on every single would be colonizer country's waters, that would sink their ships when they tried to leave port