Well if your having success with the SNGs then its probably best to stick at them! Moving up through the levels or playing 2+ SNGs at once when your ready.
Can relate to what your going through tho as I was trying to figure out cash game opening hands out bout 12 months ago and found it pretty difficult!!
If you do decide to give cash another crack, I suggest avoiding NL 6max (only to start with) as a lot of stealing and restealing goes on here and this is why its quite profitable or "easy money" for good experienced players, post flop play is also very strong.
You can always test yourself at fullring nl/limit and then move to 6max after your beating this level which is pretty simple given the resources online. Find a good online article you think makes sense to work with your style of play, then use pokerstove to tweak it by position, shove it in a document and build your own range as you go along, opening it up as you get better & grow in confidence.Good luck!
