If you have any kind of large-field, multiple-seat MTT experience, DoN SNGs are for you. They're also good for practicing those skills. The BR requirements for these games are basically the same for HU SNGs, if you play them. This should make sense because you have the same odds
of winning the same amount. Yes, they seem easy to win, especially at lower levels, but you can go on a long string of losing even in easy games. And since you don't win much in these games when you do win, you do need to have a slightly higher number of buy-ins to play these games vs. standard SNGs, when it feels like you could get away with less. This becomes more and more true when you move up in levels.
The best piece of advice for these games is to take notes... really good notes. Go back after an session and take notes if you have to (Full Tilt Poker made this really easy). Spend a few minutes before a session too looking at the games that are running and registering and pay attention to the names which are in multiple tournaments. Stay away from them as much as possible. Your notes come into play here even more. Mark down who you see making certain plays (good and bad) and the level in which you played them.
I've said this before about other formats, but you really shouldn't play SNGs of any kind without paying attention to your reward programs, including rakeback (probably most importantly if it's available). You'll base your success and evaluation based on volume. I'd stay far away from these formats if you don't have rakeback and some of your opponents might have it. The difference there will add up significantly when you get to the volume necessary to get any idea of how good you actually are. Even in the short term, your opponents can make plays against you that you can't make against them and still beat rake. Does that sound like something that makes sense to you? Do you really want to play with the equivalent of one hand tied behind your back?
If you don't have rakeback, you're better off playing MTTs where the variance is high and the rake isn't high enough to put you at a disadvantage against 99% of the players you could come up against.