In general, it is a good idea to play 60 cards, which is the minimum according to the rules. The reason for this is that you will typically have a few cards which actually do the winning for you, and if you cut down on other cards, you will be more likely to draw them.

Also, if you can get your hands of any of the fetch lands, these are definitely worth playing, even in a mono colour deck. They make you more likely to draw a land, but when you use them, they remove land from your library, making you more likely to draw spells in the later game.

I would also have a look at your mana curve. If you place your cards in piles according to mana cost (total number of mana, regardless of colour), and look at the sizes of those piles, you see your mana curve. I have made a plot of yours, which you can see here.

Your mana curve can tell you a lot about how a deck will perform. In general, if you have too many cheap spells, you will have loads of unused mana in the late game, wheras if you have too many expensive spells, you won't be able to do anything in the beginning. Your curve is pretty good, but I think maybe you should try to move the top of the curve a little more towards the expensive spells, and make it trail out a bit more at the end. I would probably try to cut a few spells at 2, 5 and 7, and maybe add a few at 3 and 4. Or not add any, if you are going down to 60 cards.