How to plan for a climb up Mount Kilimanjaro

Kili is only doable with a tour agency; it's impossible to climb by yourself. Because of this, the cost of climbing Kili is not cheap. The cheapest reliable tour I found was around US$1600, going up to as high as US$3500.
The upside is that the agency takes care of pretty much all the logistics for you during the climb. I didn't have to do any cooking, pitching tent, etc. They provide a whole support team of people to look after you (guide, porter, assistant guides, etc.)
The cost of the agencies vary depending on route and size of the group. Obviously being in a group of 20 climbers going up the easiest route (Marangu Route) is the cheapest
Don't forget to budget for tip as well. It's pretty much mandatory to tip at the end of the climb, and this can range between US$150 to $300
Routes: there are 6 routes to choose from. The cost will vary by route and you basically buy a specific route with whichever guide you decide to use. Most of the routes don't require any specialized training or skills
Marangu: cheap and popular. Staying in huts instead of tents. Same route up and down
Machame (I did this one): also very popular, and not that hard. I did the 7 day option and we were able to summit
Rongai: easiest route apparently, and not that popular
Shira: intermediate level route
Umbwe: very difficult route
Lemosho: expensive
Getting there:
I flew directly to Kilimanjaro International Airport (JRO) close to the mountain. I booked well in advance and the flight was actually quite cheap from Ottawa (around CAD$1200 round trip)
I stayed the night in a town called Arusha, a little bit west of the airport, where I rented the gear I needed for the climb and met with the tour guide. Arusha and Moshi are the two main towns that people use as their bases for climbing Kili
What's the climb like?
Big temperature difference day vs. night, and lower altitude vs. higher altitude. The first day I was in shorts and t-shirt, by night I wore a jacket. On the summit it was basically Ottawa winter day and night (-20C at night)
Altitude sickness: I experienced some signs of it with shortness of breath and fatigue, but I didn't get any headaches that some people from my group did. I picked the 7-day option specifically because I wanted to add an extra day in here for acclimatization. It's very common for many people to get severe altitude sickness in Kili (I read somewhere that this is the #1 reason people don't end up making it to the top), and the biggest reason for altitude sickness is not enough time for acclimatization
No shower: duh. I sweat a lot and in lower altitudes this got pretty gross. But as soon as you get above 3000 meters it gets cold and dry you don't really notice it
There's cellphone signal: this was pretty cool and completely unexpected. I had an international roaming plan with Bell and I was able to Facebook the entire trip. There's no power supply but I brought my own power bank
Toilet situation: most people just find a bush somewhere along the way if they need to go (I did). Always check with your guide, and obviously take toilet papers away with you. I had a little sealable bag for this purpose (sounds pretty gross I know)