Due to comments on another ? ... Another soroirty betta tank?

Nice one you've decided to get 38 gallons instead of a 10 gallon :-).

But still you need 5+ females not 4.

Either silk plants or live(research needed on what live plant to put in) no plastic plants as they rip the bettas fins and tail.

Lots of hiding spaces

Gravel or sand? Your own preference really

Filter not sure on make but you'll need one that doesn't have a strong currentr as they are not strong swimmers.

What kind of recommendations would you like?

4 female bettas for 38 gallons is good. That provides them with plenty of space.

I personally like to use real plants, but that will depend on how much care you want to put into the tank, as well as your lighting.

Gravel, definitely. Sand is harder to keep clean, in my opinion.

Get a filter rated for 40 gallons. I personally like the Penguin filters, but I've also heard good things about the Aquaclear filters.

Make sure you get a heater that's 200W. I would recommend Rena or Marineland brands.

4 females in 38 gallons is good.. recommendations.. make sure they get along although they're females so they probably will..