You should try to have a game plan or clear win condition and build your deck around that. Alongside the advice of soren841, you have several cards that are fairly weak with no visible reason to have them in your deck (
Goblin Roughrider and
Thundering Giant stick out as quite unnecessary cards).
You also have cards that are far less powerful than other cards that are available (not sure if you are building from cards you own IRL or not, but there are far better alternatives to
Sip of Hemlock or
Geist of the Moors).
Lastly, you should aim to only have 33-40% land at most really for a standard deck, and splashing a single blue mana source for a single blue creature seems unnecessary, you should either add more blue and have it as a more significant colour, or drop it entirely.