You only have 10 Mastery points so you're pretty much going to want to grab the 3rd tier mastery in whatever tree you go and then either dump the last point in the same tree or grab one of the summon spell masteries in another tree.
Mage: Offense tree - 4x Mental Force, 4x Cooldown Reduction, Arcane Knowledge. Then the last point probably in Support tree - Summoner's Insight for the reduction on Flash (which you don't have yet), Ghost, and Clarity.
Fighter: Offense - 3x Brute Force, 1x Summoner's Wrath, 4x Alacrity, 1x Weapon Expertise, and then Summoner's Insight again.
Tank: Tank tree - 3x Hardiness, 1x Resistance, 4x Durability, 1x Veteran's Scars, and then either Summoner's Resolve or Summoner's Insight.
Support: Support tree - 3x Expanded Mind, 1x Summoner's Insight, 3x Meditation, and then in Tank: 3x Resistance (the 3rd tier skills in Support aren't great at your level).
There's so many item builds that it's a bit trickier there. Starting though, you probably want to go either Doran's (whatever) or Boots + 3x pots. Using the recommend items usually isn't the worst thing you can do; just get practice in and see what items you like and which you don't.
As a final note, you're going to have really terrible mana regen at your level so don't be afraid to take Clarity or buy mana pots and mana regen items if you find yourself low on mana all the time. Also try to make your shots count since that'll save mana too.