Welcome,
$400 ? Sounds great to me, good 1st bike also, size and all.
You learn a lot about bikes in general with very little investment, such as maintaince, and so on. also when it gets tipped or fall over, (which usually does happen) it's not like dumping a $4K + machine.
You can lose $400 evey 6 months in value of of a new bike. If it lasts 6 months, and you walk away from it, your still ahead. Besides there is enough $$ left over for some good gear.
Make sure it's mechanically safe, then work on the cosmetics.
1st step in making it nice is, keeping it clean and stop any oil leaks, if any.
Polishing the chrome and alumniun cases, can take the eye away from other flaws, a good time to try out different cleaners and polishers. If there is any scratches and dents, just take care of them 1 at a time. Paint is good, but usually towards the end of my list.