Besides the general rules I have for PCs in Felltower, I have added a few others.
For starting PCs the following rules apply.
If it's not on your main template, you can't have it.
I do make small exceptions. The Ferocious Beard perk, for example, makes perfect sense as a starting perk. I'm fine with people taking Reach Mastery if they have a two-handed weapon and don't feel like waiting exactly one session to get it. I'd possibly consider other ones, as well.
Spellcaster perks, though? Little chance of them.
I do make a big exception for the Thief. I think it's a much richer, fuller, and more immediately effective template with the Power-Ups, so I allow them, per this discussion and the ones linked here. A thief that starts with Sensitive Touch or Backstabber is a much more viable character in my experience.
Not a thief? Stick to what's listed on your template to start with.
The general idea here is that you can make a character with just Dungeon Fantasy 1: Adventurers (Or Barbarians, or Ninja for Assassins.) You don't need any other books. You don't have to be fully conversant in the options to make a viable character. The rare exceptions are perks like the ones above, and I'm able to just suggest them as the GM if I think they'll in-concept and the player doesn't realize they are out there. One book is all you need to keep up.
That is, no cross-training lenses. Template-specific lenses (like those in Barbarians) are allowed.
I do this for a few reasons.
One is that, at full cost, basically Knights and Swashbucklers can afford lenses. So it becomes a narrow set of templates that can afford to lens out right away, and it encourages people to do so because you can stack Swashbuckler onto Knight, say, just so you could get more sword skill off the bat.
Another is that, while I like the concept of cutting down duplication to allow easier purchase, it feeds into the first part and feed heavily into the next one. So not allowing it reinforces point one, and if I allow it . . . keep reading.
The third and probably most important reason is because that allowing lenses rewards the players with the most time to investigate cross-template synergies and long-range Power-Up synergy goals. Since I'm gearing the game to casual play, I want the folks who just say, "Give me a Knight with a mace and shield!" or "I'll run a Druid" just to be able to do so without worrying that they've already given up ground to the more rule-expert guys. That the rules-expert guys have come up with some totally amazing synergistic combination between this Knight Power-Up here and that Swashbuckler Power-Up there and this here Martial Artist Chi Power is fine - they're more than 100 points away from that. They're just as Knight as you are, to start, no matter where they plan to go.
No Special Customizations
If it's on your template and we're using it, it's on your template and you are using it. I don't allow customization. No extra disads above the count. No ditching skills just because you can't think why Mimicry (Bird Calls) or Writing or Physiology (Undead) can help you. Find a use for them.
I will allow thematically appropriate changes - this is why, for example, we had a Martial Artist with Gigantism. I've allowed different disads for some templates to swap in ones that seemed to fit the concept of the character and the template. But I haven't allowed new advantages, extra powers, or dumping required disads to open up more options for a template.