If you fancy a real taste of the great outdoors - away from the mini suburbia of campsites then wild camping is the way forward... the views are much better and it won't cost you a penny and you'll genuinely feel part of the countryside, not removed from it.
I pretty much solo wild camped for 3 months from the UK to Mongolia & Siberia and back last summer. I just stopped when I felt like it. My general advice is:
1. Try to stay away from towns and villages: either everyone should know you are there or nobody. You don't want to be bothered by the local drunks.
2. Drop any paranoia as soon as possible, relax, no-one is after you. This will probably take a few nights but the sooner you do this the more you'll enjoy it. Don't listen to the horror stories and the naysayers. Use your common sense, if it doesn't feel right move on.
3. Stop early enough to be able to find somewhere else if the spot turns out to be a bad choice. You don't want to be looking for somewhere in the dark. If you do you might wake up to a glorious surprise view or you might find yourself somewhere very odd.
4. If you're on a highway, when you turn off try and take at least two more turns offs before you stop - this way you're well away from the main highway and anybody that might have spotted you turn off. Of course you might not be on a highway.
5. Camp in groups when you can. I came across an American couple doing the Mongol rally and we camped together for a bit until going our separate ways - it's good to have some company and security.
6. Don't be afraid of the locals: farmers/sherpherds might come across you. Be friendly and polite and if possible offer them a ciggie to break the ice. Expect curiosity in you, your bike, your gear and your trip. In my experience they'll make a little small talk and be on their way.
7. Leave the area as you find it. If you can't burn or bury your biodegradables take them with you. Don't contaminate water supplies, dig a latrine.
8. Be discreet: try to avoid loud music, bright lights, massive fires and engine revving. Cover your bike to avoid the shiny bits... shining. I stumbled across and camped with a local fisherman in Russia, after numerous vodkas we broke all these rules, LOL.
8. Try different places and find out what sort of place you like to camp. I found that I liked camping near water: lakes and rivers, so that I could have a swim at the end of the day. So I had a look at my map in the morning to find such places roughly where I wanted to stop for the night. Lakes surrounded by forests was my ideal spot.
9. If the legality of your camp site is questionable arrive late and leave early. If you can ask permission do so but you do obviously risk them saying no. Alternatively, if nobody knows you are there and you follow all the rules above then as far as I'm concerned what they don't know won't hurt them - but that's your call.
10. Be patient, recce a site, wait around for a bit before setting up. If it's not right move on. You'll find some beautiful places to camp but don't expect this every time. Sometimes you'll have to be satisfied with somewhere flat and dry.
11. Take ear plugs in case your campsite (wild or organised) turns out to be a noisey one.
12. Take advantages of opportunities. One time I was struggling to find a campsite when I stopped at a petrol station to get a drink and have a breather when a local told me that 1/2 a mile away was a bike meet with free camping - that was a noisy night but the spot by the Adriatic was idyllic.
13. Whatever shelter you use try to use subdued colours, you don't need military DPM, but a bright red or blue tarp/tent isn't exactly inconspicuous. They're great if you want to be spotted in an emergency but stealth is the name of the game when wild camping, especially when solo.
14. If you have nervous friends and relatives take a spot satellite tracker and send them an 'ok' message when you do stop for the night.
15. I've never been asked to move but if you are just plead ignorant, pack up your stuff and leave without argument - better safe than sorry.
16. Use the local knowledge: check out the HU communities. Some areas just might not be safe or appropriate for wild camping either because of the terrain, the weather or the people. Sometimes you might just be better off in an organised paying campsite, a hostel or on someones couch.
17. Have fun. Its a great way to travel and cheap too!

Mongolian Daisy Meadow

By a river somewhere in Austria

Arrive late...

Leave early... bloody trains!

Adriatic Coast off Croatia

The Black Forrest is certainly black

Dried river bed on the Mongol Steppe

I was lucky enough to find this same spot on my return leg... it's a very secluded but free public camping area in Siberia

There not idyllic this Siberian wild camp was only 200m from the main road, albeit a very quiet main road, behind a massive bush... it worked

I love the woodlands

Touristy public camping area that I blagged onto for free, noisy but...

...it had a pretty view and was the coolest clearest water I'd seen,I had a great sunrise swim to wash away the hangover.

Break the rules when you can...

Group camping has it's perks

Sometimes there are no highways...