There's good advice in the comments (try asking in chat), and this question may get closed as too broad but I can give you some suggestions for how I would do it.
First make a list of places / countries you'd like to see (or things you'd like to do) and try and put a rough order of priority on it.
Next go through the countries on the list and look up the visa restrictions -- do you need a visa in advance, can you get a visa in the neighboring country, how long does it take? If there are visas you need to secure before you start then you'll need dates and travel plans for those countries which will give you the rough start of a schedule.
Then look at how to get between the countries, you probably want to avoid flying so here's the obligatory link to Seat61.com which will help you work out which countries have connections to each other. From there you can plan a rough route and schedule -- you can still be flexible.
If it was me I'd try to have some definite points planned -- i.e. I want to be in this city on that day. Look at what's on in the different places in advance to give you an idea (nothing worse than showing up in a city and discovering you just missed the big festival/event by a couple of days). Maybe book a nice hotel so you know you have a bit of luxury coming up if you're in hostels the rest of the time.
I also look for organized tours that I can join, particularly if they cover several countries -- not only will they help with the travel and visas for that bit, but it also means that you'll have a group of probably like-minded travelers for a while -- this can be a great help if you're getting a bit bored of being on your own.
There are a couple of 'classic' routes that do what you want -- either the Trans-Siberian / Trans-Mongolian or the Silk Road. You can google them for organized tours, other peoples schedules, etc, etc.
Once you have a bit of a idea you can ask more specific questions here and people will be glad to help.
Oh, and have good travel insurance, and have electronic copies of visas, passports, documents etc online (I use Google Docs, if you use that for your schedule you can easily share it too).
That's the generic advice, now a bit of obviously-biased advice -- don't ignore the Philippines, it's a bit of a pain to get to but if you're in the area it's a short flight and it's a great country that doesn't get too many tourists at the moment. It's also pretty cheap. And since it's a bit more western than other nearby countries it serves as a good place to stop off if the cultural shock of Asia is getting too much (also a good stopping point if you're heading to Australia from somewhere in SE Asia).