I am a new player to Arkham Horror. I will be starting the Path to Carcosa campaign. Are there any other packs that you would recommend for the player cards? I am not sure yet if or how many people will be joining me. I have not settled on an investigator yet. I currently just have the core set, but will pick up more when I get paid.

There is always at least 1 good card for someone in every pack. Since you are starting the path to carcosa campaign, you should pick up that cycle first. Then you can look through other packs in the other cycles to see what could make the deck you are building toward better.

Ultimately, if you want all the options, you will need everything. But once you decide what you are doing, you can narrow down what you need.

I have decided that I will be playing William Yorik, the Gravedigger. If I can not find another person to play with, then I will play a different investigator as well. Are there any packs or expansions that you would recommend for Yorik specifically? That is outside of the Carcosa line.

A lot of what Yorick needs is in the Cores and Path to Carcosa deluxe box/cycle, but here are some options. Blood on the Altar of the Dunwich cycle is where all the permanent booster assets are, for Yorick that would be Scrapper. The Dunwich Deluxe box has Peter Sylvester, which is one of the more popular Survivor allies. Threads of Fate, the newest pack, has Scene of the Crime, which can help with clue grabbing.

But then you really have to ask yourself: are you willing to pay 15-25$ for a few cards you are going to put in only one deck?

Before you start spending more money on this game (as it becomes quite expensive very fast) I'd recommend you to stick with the Carcosa cycle and see how his game evolves for you and your group

Well, I would definitely agree with C2K and say that Blood on the Altar is a supremely good choice. Not only does it have Yorrick's permanent talent, Scrapper, but it has all the other classes permanent talents as well... which is going to be very useful if you play 2 handed solo... And you also pick up Lone Wolf which is a great card for those who can take it (but Yorrick can not, unfortunately). Prepared for the Worst is a decent card too. Maybe not an auto-include every time, but I definitely would at least think about it when building any class with access to the Guardian cards.

You don't really need the extra player cards though...and they'll be even more fun and surprises as you make your way through other campaigns.

Yorrick can do some very surprising and deadly things with a knife. ?

Yoric really gets pretty much every card he needs from Carcosa. Cards like the .45 upgrade, Fight or Flight, Madame Labranche. And the rest from the core set.

A second core takes priority over all else I say, if you cherry pick just one Dunwick pack then the standout pack is "Blood on the Altar". It has all the permanent skill booster cards (Scrapper is absolutely great for Yorrick). It has Lone wolf, Preposterous Scetches and Prepared for the worst too, all good and commonly played cards (And that last one can help you find the upgraded .45).

Regarding the necessity of a second Core set: there are numerous threads to be found about this topic on reddit, bgg and here of course

I have been using him in Carcosa. I have been using Red Gloved Man with Charisma and Lebranch. Its quite killer.

I would goto Arkham DB and look around at the higher xp cards and see if you want any. I think you can run most invetsigators just fine with two cores and any one cycle.