Until you are level two you want to play as passive as possible. You want to primarily last hit minions with the sniper and occasionally last hit with the pistol for life steal if low. Once you hit level two you want to try to take advantage of the power spike by poking q's in with the sniper, It will deal really high damage for level 2.

1 Sniper Rifle:
The sniper is really good for poking and good long range damage. you want to AA and weave in q's for really good damage with the sniper. But be careful you can burn ammo fast with it. Also really good at taking out low health targets.

2 Pistol:
The pistol is really good for when you are low or wanting to stack chakram. It is also a really good damage source.

3 Grav Cannon:
The grav cannon is a strong utility weapon. For example in laning phase you can drop a AA on someone and stun them using your Q. Then your support can get a free CC on them most likely resulting in a kill.

4 Flame Thrower:
Easily his strongest weapon, It has good wave clear, Good damage, and great synergy with other weapons.

5 Chakram:
The chakram is a little bit of a weird one. you can only really use it as your primary while cs'ing. But that doesn't mean its bad because trust me it isn't. If you can build up chakram by using other abilities you can use the multiple to nuke people. Also you can use his turret to get easy marks on people.

There are so many combos that i could be here writing all day. So I will just go over the best I have found. A real strong one is Flame thrower Q into sniper Q, That combo alone can shread a entire team if multiple are hit. Next is Flame thrower q into Grav Q. You can root the entire enemy team using it so its a great utility. Next is Pistol Q into anything you can synergize anything with it.

Once You get Runan's hurricane His entire kit comes into play. Grav cannon becomes busted and so does every other Weapon. So once you get this you can truly experience Aphelios