You certainly have come to the right place. This is indeed the place to ask for help on strategies.
Blue seems to have the advantage and also you get 40 when you have cards, you don't have a set which means you are in a weak position. At 40, a player can significantly destroy the other and gain the other hand. You didn't mention what is the situation with cards for Blue. Has he just cashed in. How many cards does he have?
Using standard rules, you probably get 12 armies to place in. Usually, you should focus on the concentration of armies of your opponent. That way, you reduce his options so then he cant take the initiative with a large army to attack anything. In addition, he can become demoralised having lost the big bulk. So in this case, try to reduce the 35 armies in place and go from there.
If you go for NA, you may also be able to reduce the number of your borders 2 three and protect a large number of your territories. The continent bonus is not really important at this level, what matters is to be able to manoeuvre and reposition and let the other guy think you are more powerful than you are. He may attack Africa or Europe, but you have since strengthened your position in other part and can count on it in the next round.
Risk Map: me-vs-my-cousinhelp-needed_2 --- Open Copy in Risk Map Editor