Hey there! Welcome to the forum!
What size is the tank you want to use? Are you going to use a filter?
Make sure you get a heater!
When you get decorations and plants, make sure the plants are silk or real. Plastic plants are like razors to little betta fins. The decorations should be smooth, no jagged edges. Bettas love having a place to hide, so a little cave would be perfect.
To dechlorinate, use a water conditioner like Aquasafe, Stress Coat Plus, or Seachem Prime, which are all highly recommended by members on this site.
Any questions, feel free to ask here :)
Welcome. I completely agree with MadameDesu and I would add to make sure your tank is cycled before adding your fish. When you say decent size, what size are you talking about? If you want your Betta to live a long, happy, healthy life I suggest you have a minimum of a 5g tank.
That's not a horrible size. Everyone has different opinions on tank size here.
You can put a betta in a 1.8 gal, but it would mean more maintenance in the long run because it would be almost too small for a filter and probably wouldn't hold a cycle. That would mean changing the water two or three times a week.
A cycled 5gal, in comparison would only need about 30% of the water changed once a week.
It's up to you. If you're willing to do the changes and can't afford a bigger tank, a 1.8 gal would be fine, I think.
All of this is strictly my own opinion. You may hear differently from others.
A 1.8 is a good size tank for a single betta.. if you got one of those unfiltered 3 gallons it would require the same amount of cleaning as the 1.8.
You don't want to over clean your tanks, as the water can actually be too clean and in the long run not be as healthful to the fish. I have some tanks that are that size, and have had no issues with health due to the tank size nor with proper water changes. Anything under 5 gallons won't hold a proper cycle, so you won't have to worry about that.
For your size of tank, recommended for unfiltered is 1 50% and 1 100% water change per week- I personally prefer doing 1 100% once every 4-5 days. But that is me, my water conditions, live plants, the type of food I feed, etc. You will find out what works best for you.. but the general rule of thumb is what I listed.
Depends upon what type of plants you are going for.. in a small, unfiltered tank I would stick with the easy low-light variety such as Java moss/Java fern, anubias, etc.. those types don't require filters nor much light.
Going with live plants will cut back water changes, as the plants will use the fish waste as fertilizer. Yum. Which makes it easier on you- so once you decide if you are going with live plants, what type and how many you can let us know and we can help provide a good cleaning schedule if you wish.
None... a lot of people just tie them onto rocks or driftwood to anchor them down, but even that is not needed. Why they are great for small tanks.. I forgot to add they don't need substrate on my last post.