I know this thread is a week old, but I figure I should chime in here. OP, Roman, I am on your friends list and have been for awhile. If you have any questions please feel free to ask me in game- I will answer them to the best of my ability. You are also doing the right thing by being on this forum. You can learn a lot, you just have to have an open mind to what everyone is saying. The people on here have played for a long time in a lot of different styles. They know what they are talking about. While there is some RNG aspect to the game, I haven't spent a dollar on the game, and have finished the event building on every event since I joined this forum. A lot of it comes down to being smart with your resources and planning ahead.
When it comes to GBs and contributing, a good way to start is to join a guild that uses swap threads. If you don't have one, my guild has very active swap threads, and you are free to join. (I can send you an invite if you wish). When you join the swap threads you will at least be guaranteed the amount of fps on your gb that you contributed to another gb. If you are rational about what gbs you chose to add to you can also easily claim some rewards spots. This will help you bolster your fp reserves and get your buildings up in level. If you have any further questions let me know.