For an all around blade I would get a 1/4 inch. You can do pretty tight curves and do most cutting. On my 14" saw, 75 percent of the time I ran a 1/4 inch blade because most of what I did with it was curve cutting.
As for brands, you pay for what you get. If you are starting out, it doesn't hurt to go cheap to get a feel for what you like and don't like. Personally, I have a hard time recognizing or knowing when a blade is dull or shot. I will say it is always good to have a spare on hand. I don't remember if the saw you got is a 2 or 3 wheel, but if it is a 3 wheel, expect to break lots of blades DAMHIKT.