When the game starts you want to wait until 3 to really start poking and winning trades with the other laner. When you hit 3 you want to start harassing the other player with your q. If he intends on trading use your q on him then immediately use your e on the orb and the player, while they are stunned pick up another orb(you should be using q through out the fight) and land it on them for a guaranteed half health trade for them and nothing on you in return. When you have your 6 you should initiate with the trade I just explained then ult ignite for first blood. During the mid game you should be doinh as much roaming as possible... helping top mid and even counter jungling, you want to get fed early. During a team fight you should intiate on the other team for your team. No dont get into melee range and ult mundo. You should q at max range and aim your e to land a stun on an enemy player... syndra has one of the farthest stuns in the game if aimed correctly. After the tank has gone in off of your stun you should spam q and attempt to ult the adc/apc.Continue this until you take towers inhibs and win the game. Intially it will be tough to get the combo right but normals are great practice.

When building syndra you want a mixture of a ton of damage and some defense.So this build order is in my opinion the best way to do this.some items like VS are interchangeable but for the most part you should follow this build for victories.

For the masteries I typically run 21 in offense and 9 defense for damage and sustain in lane. If you tend to spam I suggest running the 9 on utility instead but it should not be necessary the build itself should keep you from getting mana hungry.