upgrading to a bigger tank

Question
I have a 10 gallon fish tank with 5 glowlight tetras, 1 dwarf gourami, 2 glass fish, and 1 ottocinclus catfish. They are all small but i want to upgrade to a 50 or 55 gallon fish tank. What would be the best way to do this?
Oh yeah, I also have a problemb with gourami. Every time I buy another gourami to accompany the first, the older one dies. This has happened two times now. Do you have any idea why this happens or what i should do about it? Thanks for your time.

Answer
The best thing you can do with the gouramis is keep one per tank. They are very territorial fish. Don't try to mix colors as they will usually fight in that case.

The best way to move them up is to save all the water that you can from your other tank. Set up the 55 Gallon and cycle it for at least 2 weeks. (let it run with nothing living in it) When the water levels have gotten to the proper level take out enough water so you can add the water from the 10 gallon this will help the fish keep their beneficial bacteria.