The original post seemed to be looking at character Aspects and there are some good responses to that. Did you have any problems with any of the other types of Aspects?

One idea I remember from the Legend of the Five Rings mass battle system (the version where it had it's own system, not the d20 thing) was having a general roll to see what happened in really big battles. These wouldn't be like 10 ninjas or something, these really were army on army battles that your characters were stuck in the middle of.

It's been years since I used this but as I recall you randomly rolled the die to see what happened around the characters and compared it to a chart. Front line or otherwise more dangerous areas had modifiers to make worse things happen to you and vice versa for being in a more protected rearward area. The consequences were things like varying amounts of damage which weren't huge but could add up quickly, facing off against a noteworthy foe (couple rounds of normal combat, not a death match), and I think on the more pleasant end there were opportunities to push the enemy and gain an advantage in the battle. Think that hurts their morale and really good results for you do more damage to their morale, eventually routing them.

I think there were rules for being a general as well but as my group never had a reason to use those I'm not certain what they were. I think it'd work if you ran it as a modifier on the same chart you're rolling results on for the PCs.

If this sounds interesting to anyone I could probably whip up an example of this kind of system for DFRPG but it would take a bit of typing and probably a week or two to get something worth looking at. Not certan how much it would get used. The novels have two battles that would be large enough to use something like this for but they're part of epic, world altering events. I'm not sure things like that would pop up very often in normal gameplay.

"My left hand is not mine realy". He make a bargain with one of Unseelie Sidhe to gain knowledge about his father (he is an orphan and his mom die in jail). Cost was control of his left hand when he actually see his father. It is a great story hook and awesome dedication from player. But i think it is not so good formulated aspect.

I think I'd recommend altering that a bit. Something to reflect the deal more. It doesn't change the story but if you focus on the deal it will encourage both you and the player to think about other ways it can come up. Maybe when dealing with Winter fae he can reasonably claim he has some idea what to expect. You might be able to compel him to consider gambling on a new deal as well. After all, he's managing this one alright isn't he? So what could it hurt? 

Didn't look at the others, sorry... Seemed to have enough responses on those.

Haven't run DFRPG yet... So take any opinions with a grain (or more) of salt.

That said, I tend to think it's easier to start lower powered. Your story isn't irrevocably harmed if you decide the power level is too low and you'd like to "fast forward" a bit to a point where the characters have more experience.

What Guldor said about the experience of the group with DFRPG will matter a lot. How they manage their Aspects and fate points seems like it could make a rather large difference, not to mention using maneuvers and cooperative tactics to deal with more intractable foes. I know the Dresden Files novels don't do this real often but you could always borrow a page from the superhero genre and throw a group of enemies at the PCs rather than one big one (superhero team meet... supervillain team! *cue evil laughter*). Part of the reason this doesn't happen a lot in the novels is because Harry is often going it solo. Which as every good gamer knows is tantamount to asking the GM to do evil things to you.

You shouldn't have too much problem implementing new ideas into the Dresden Files universe. It's actually pretty open when you think about it. Just within the novels we have fae, Lovecraftian horrors, and the Norse pantheon all showing up alongside ideas from the Christian faith. Given the rather complex treatment angels have been given in the series so far I think you're totally safe having them just not answer any questions about who they serve. It's not like they give straight answers on any other topic, why should this one be unique?

Ultimately the only thing you have to do is be respectful when you handle other people's beliefs. Some easy ways to do this are to avoid questions like whether Yahweh and Allah are the same person, how powerful deities are in relation to each other, etc. When big, existential stuff comes up in the novels, most of the time answers are not forthcoming. If they come up in your game, try giving a generic answer like "That you've asked the question is more interesting than any answer I could give." or "That isn't the right question. What you should be asking is <insert question more directly appropriate to the situation here>".

You may get something out of this write-up, not to mention the other entries on this site:

http://www.faterpg.com/2011/stress-consequences-and-the-fractal/

Basically it's a "hack your own" for Fate-based RPG's. Of course they don't cover every area of the system and it's not an organized how-to by any means. But the stuff they cover they do a rather good job at. Good enough to jump start ideas in other areas I think.

This is general advice as I haven't run DFRPG yet. But I have run solo games.

One thing that I think helps is giving them a companion that they can interact with easily. A solo game is going to focus pretty heavily on the lone PC for obvious reasons. Giving them an ally to talk to lets your player still play the game while they're trying to solve a puzzle. The challenge with an ally character is making them seem more like a friend who has their own strengths, weaknesses and areas of knowledge rather than a GM plant to periodically wave around a "Plot this way -->" sign. The player can also help you design this NPC by including them in their story if you do the usual character creation route before play starts.