Hi! I am an UNRANKED player who hasn't played Summoner's Rift in at least a month, and have NEVER played Aphelios in my life. (If I do play ranked, I'll probably be Bronze at best.) I don't know about you, but I think that makes me pretty qualified to write an Aphelios guide. You see, all these Challenger / Grandmaster guides are pretty similar, and only give you one approach to playing the game. I come with an alternative approach that may give you some new insights.

PROS

You can flex your IQ just by locking in Aphelios in champ select. Now your team legally cannot flame you based on intelligence. You're the one playing Aphelios, not them.
You have 5 weapons when most others have only one, and two at most.
You don't need to worry about forgetting to use your abilities because you have fewer abilities than other champions!

CONS

If you are a heavy chat user, you cannot use chat as Aphelios as you are mute. This means you cannot flame your team through chat.
Your brain may melt from the high brainpower needed to play Aphelios.

Is this a good time to say I've never played this champion?

Right from the start, you should keep switching weapons back and forth in front of your enemies. This will intimidate them as they realise they only have one weapon compared to your more than one. However, take note that this is not as effective when facing champions such as Jayce or Jinx who can do the same. This could also backfire if laning with a very emotionally sensitive support as they may feel discouraged in their own abilities due to their lack of another weapon.

Throughout the game, you may be tempted to use chat, whether to strategise or to flame. This sounds like a smart idea in theory, especially in /allchat, as your enemies who thought you were mute are scared when realising you aren't. However, this is very risky, as they may then submit a ticket to Riot reporting you for cheating.

It is okay to stay away from your team. You won't be lonely unlike other champions thanks to Alune.

If you take Waterwalking as your rune, always stay in the river to maximise the bonus. This is especially good if Nami is on your team. Ask Nami to keep ulting you.

Don't die.

So there you have it, a most undefinitve guide to Aphelios! I hope this has been helpful in your climb to Grandmaster.