I'm not in Beginner's world, but as having finished 3rd in company value in last GW3, I can give you a few pointers on how to grow fast :
Begin by leasing old crap with decent capacity. in big airports, old A320/B737/MD80 are kickass for a beginning. Lease them for a short while, and be sure to get rid of them before their D-Check.
Begin with the low-hanging fruits : short lines with a lot of demand. Later in the game, CDG-LHR will be overcrowded, and won't make a lot of money. But early in the game, it's a gold-maker. If only 30% of demand is filled(which will be true for the first few weeks), then even at 0 route image, your plane will be full. And make immediate money you need to order other planes.
Begin by spreading routes. If you focus all your efforts on a few selected routes, you will cover more demand from them, and that's not good, as your load factor will plummet. Covering broader just after the inital effort on biggest routes gives you more bang for your buck. Additionally, you're less vulnerable to an attack.
Be agressive with your scheduling. Try to stuff as much flights per day as possible. Note also that in beginner's world, you can even safely land/take off at night. I advise against this practice, as it gives you bad habits, that might kill you in real game worlds, but some do that, and in beginner's world, it makes them even more efficient.
Be agressive with pricing. But not with opposition - with your customers. Milk them like the cash cows they are. As soon as Load Factor is beyond 90%(95% for high-density seats), increase your prices. Efficient when done company-wide. Very efficient
Optimize your seating. That's quite micro-managey, but having the right number of business seats helps a lot. When cumulated with price micromanagement, it can be the difference between life an death. In last GW3, I started in CDG, and had a lot of opponents(like always in such big places). I micromanaged my business seating and its pricing, while opposition didn't bother with it. The simple fact of micromanaging business seats prices(not having them - just micromanaging their prices) made 25% of my pretax profit. 25% of my financing power. 25% of my growth capacity. So I added more planes than opposition, with more profit per plane, and I ended up overwhelming them all. I didn't pricewar them at all. Quite the opposite. I just milked my customers as much as possible, covered every possible demand as if opposition didn't exist, and after 18 months, they were all dead.
Be ruthless. Be aggressive. Don't lower your prices. Be everywhere. Begin with short, juicy routes. Be better than others.