A sim CAN AND WILL HELP. A sim will not teach you all you need to know. I own and like RealFlight G2. I find it about as close as you will get to the actual act of flying. Sims do not take into account that your plane may not be trimmed out. In addition you have a LIMITED view. Imagine a box over your head so you can only see straight ahead - you have no side vision, that is what you have on a sim. The better sims (the ones that cost $$$) allow you to program in weather conditions, whether you are flying off of pavement or grass/dirt, allow collisons with objects, random flight failures and how realistic (or unrealistic) you want the plane/flying to be.

If you plan to start with electrics, I suggest something like a Slow Stick. One thing you should be aware of - the MAJORITY of electric trainers CAN NOT DEAL WITH WIND much over 3 - 5 mph. This means your flying is pretty much going to be early morning or early evening because the wind is low then.

I fly both glow and electric. I learned on glow and when I started in electrics I had no problems.
The MAJORITY of 40 size glow trainers will easily handle 10 mph+ wind and are easier to see due to their larger size. The downside is they are noisy, require a much larger area to fly in and need to be cleaned off at the end of the day (no biggie, 5 minutes with some Windex and a paper towel).