RISK! Experts, I need some advice?

So, recently, I became addicted to RISK. I need some help with my strategy, however. What I usually try to do is simoultaneously conquer Australia and South America. I would then fortify both there borders. I would then attack and take Central America, to prevent anyone from getting the Continental Bonus of Na. I would then move to either Africa or NA from SA. If I took Africa, I would then take Europe and then go back to NA. If I took NA, I would go to Europe and then go to Africa. (Unless there is an exceptional situation, I would go for Africa first, as I would only have to deal with enemies from Europe, and I can get a quicker continental bonus). I will then continue an advance, in which 1 turn I will rush and thinkly spread my forces, then reinforce, rush, reinforce, etc. Sometimes this works, but sometimes it doesn't. This is because I sometimes get trapped in SA. Do you guys have any advice? Thanks. Also, sometimes I will fall into a pattern of a battle over Central America. I take it, a North American enemy takes it, and back and forth. It is hard to prevent this when you can only defend with 2 at a time. Any advice would be appreciated.