Originally Posted by wile2k

I'd suggest starting with a car that is similar (or at least common) to what others at your club will be racing with. It will make it easier to get help or flesh out setup problems that you might run into. 12th scale can be finicky, sometimes something really small will make a big difference.

CRC GenXL and Associated 12R5 are pretty common and definitely competative. BMI with the old school front end is pretty straight forward for someone to help you with. Speedmerchant with the old front end is again straight forward. The newer front ends might be harder to help you with until people have them figured out a bit better.

Tekin RS speed control is common and pretty well sorted out (probably go with the RS / Tekin motor combo that is correct for the class that you'd be running, i.e. 17.5 or 13.5). I'm going with the new Novak Kinetic 1S and Ballistic combo but it isn't as well sorted out yet since the Kinetics are pretty new. The AE Black Diamond is interesting. It is really spendy and isn't computer programmable (has to be sent to the factory for firmware upgrades), but it's finite settings (have a handful of "profiles" for the various functions) might be, in a way, easier to setup and it is unquestionably fast. I'm not necessarily suggesting it, but it might be worth putting in your research queue.

Servo, Futaba 9650 or JR 3650 are the tops of my lists.

Thunderpower packs are well thought of 5000+MAh 50c (although I went with a budget pack from Protek 5000MAH 40c for less $ as I don't think I'll notice or need the 50c rate running 17.5). SMC and others make great packs too, probably won't go wrong if you just do a little research before buying. These are 1S LiPo hard case, but you probably already get that.

Depending on class, you'll want pinion / spurs capable of 60-100mm rollout. Plan to get a bunch of pinions, probably from about 40-60 tooth and a couple spurs 76,80,84 (car will probably come with 88). If you can do some research on your motor / class (ESC rules, sportsman or open) / track size, you can probably slim those down to maybe 2 spurs and a dozen pinions...