How long is a piece of string

When I want to set up a new tank I usually look at what my interests
a Biotope; Planted; Regional; Breeding; Species......

I know it sounds a bir odd but check out what sort of things interest
you. Its not going to be much fun, not to mention costly if a couple
months down the line you decide not to go for what you've got. I know
when I started I stayed with soft water species from either the Amazon
or Far East as I had a readily available supply of soft; acidic water.
I know other ppl who started with livebearers and just got stuck there.

To cut a long story short, try and figure what direction you'd like to
go for, do some research and then make a decision.

Hope that helped.

;J