I know a lot of people start doing toddler bed when the munchkin gets to the point where they are trying to escape their cribs. We made the decision to move to toddler bed because I need the crib for #2 and I wanted #1 to transition out of it far enough in advance that he didn't associate new bebe with "losing" his bed. Some people are content to leave the kiddos in the crib until 3 years old.
For the actual process we went out and bought a twin mattress and box spring, one of those bed rails, two waterproof mattress protectors and two sets of sheets. Since he's not even 2 yet I just put the mattress/box spring directly on the floor so he can easily get in and out and if he happens to fall out it's not so far to the ground.
The actual transition was pretty easy for us. He spent a lot of time in our bed (we co-slept until he was 5 or 6 months, then we did a couple more months where we'd snuggle him to sleep in our bed before transplanting him to his crib) and we've done bedtime routine in our bed ever since (butt change, pajamas, tooth brushing, bedtime story, etc) so he's used to the idea of an actual bed.
Pretty sure I made some posts on this thread about the first couple of days in the big boy bed. He does play for awhile before going to bed. Less time now that it's getting dark early (and we put painters tape over his light switch so he couldn't turn the lights on). With the exception of one time he has always crawled into his bed to pass out. We had to make some furniture adjustments in his room (removing his lamp, repositioning furniture, window coverings, etc) but nothing major.
He tore his mini blinds to shreds looking out the window. Solution: Leave them open, shorten the strings so he can't get to them.
He broke a curtain rod by yanking on the curtains. Solution: Take the stupid curtains down. They were cutesy decorative things hung on a $2 Walmart curtain rod anyway.
We had to move his nightstand over so it was almost flush with his bed. He'd stand between bed and night stand looking out the window until he passed out. Unfortunately when he did this he was still half standing up (feet on floor, torso flopped over on bed) and he usually woke himself up sliding to the floor.
Other than little things like that (that you'll discover along the way) just make sure it's as child proofed as reasonably possible. Outlet covers, anything breakable removed/placed waaaaaaay out of reach, strings from blinds, curtains, etc shortened so he can't reach them, child proof door knob cover or gate to prevent nocturnal escapes. He'll get into absolutely everything for awhile before he gets bored with it.
I still really wish we had a video monitor. Sometimes I'm just so damn curious about WTF is going on in there. Over the weekend we accidentally shut a kitty in his bedroom with him for naptime. No napping actually occurred and the cat is still pissed.
