Newbies are having problems because they haven't seen that world yet, where ones imagination is the limit. The idea that you can be everything takes some time to get used to. They have no idea how to break that boundary or how to play as someone else. Or what is acceptable in setting you all want to play. I think that everyone I ever played with - their first character always hugely resembled themselves, no interesting goals for themselves, no fancy characteristics.
I recently had to GM for a group of complete newbies. And I wanted to break that the first game and the first character always is only introduction. It took some work, but in the end we all had great fun. Pre-adventure work I split in three parts.
1. Getting to know people you are going to play with. I simply asked what kind of games they like (both board and computer), what intrigues them in various plots (books and movies), free time activities and of course - what they expect of the game. Silly thing that I observed - everyone said that they just want to see how game looks like and just enjoy company of others, but their gaming and book reading habits revealed good details about other possible aspects what they could enjoy from the game. As a result, it gave me an idea what to emphasize in adventure - social interactions, combat, detailed scenery, etc., and what might not work.
2. Instead of letting them figure it all for themselves, give them choice from preset themes. I prepared short introduction in universe we are going to play in and four detailed themes to choose from. "Cursed", "Noble", "Member of a guild" x2 - as rich in detail and history as possible. When they chose, I told who knows whom before game, so they can work on their relationship together (in case they took the same guild). It gave them a frame to work with. Actually after that new characters were born quite naturally.
3. Ask them work on details of their character. I asked them to create backstory for every skill they posess - how they got it? They were "forced" to create backstory (theme+details), giving them a frame to put nice characteristics in.
Before game I only gave a reason why we have to meet at inn. After that pure fun followed. Of course you can't prepare everything perfectly - you will have to observe how they play in order to make the best adventure ever for your particular group. But I think giving them a frame to work with is the best you can do out-of-game.