Upgrading tank need advice?

First, u should add the water almost to the top and get the rocks in, filter running heater set so the water is at a good temp( I keep mine at 78 degrees. Ur tank is gunna have to cylce for 2-4 weeks. And I heard that crowntail bettas are the "meanest" but that's to other bettas and I'm not sure if they are other fish. If u wanted to put ur betta in the 30 gal with some other fish u defanitly should go with fast moveing fish like danios or harlequin rasboras. As for a sucker fish, get 1-2 albino bristlenos plecos. They don't get nearly as big and there fellow relatives. And maybe a school of 5-6 albino cories or juli cories- they only reach about 2 in. And if u don't want ur betta in their- u could get the sucker fish and cories, and A MALE DWARF GOURAMI those or awesome and cool looking and not agressive at all. And the maybe a school of neon tetras or some kind of tetras. Maybe some kind of platy or swordtail. I wouldn't get guppies, I have them and they get really boring'even tho their really easy. U could get 1-2 males to help cycle ur new tank. U should make a trip to ur local petsore and get the essentials like water constioner and everything u don't have already. The biggest thing is to get ur tank set up and let it cycle until ur plants arrive and then put them in Andet it cycle for a couple weeks more before putting fish in it. Oh and when picking out a food for ur plants- get something that is high in iron. I hope I've helped:)