I would break them into two sets of five accounts each.

Create a warcraft account, using one of the ten.
From that accounts management page, use the RAF link to send an invite to your own email.
Use the email link to create an account (which is not linked to your first account).
Once that is done, use a 2nd account to upgrade the newly made RAF account.
Now go to the new (account B) account management page and send another RAF invite.
Repeat the process, until you have five total accounts used.

The links will be like this:
A -- B -- C -- D -- E

Ignore the other five accounts for now.
When you're done with the first five, you can repeat the process on the remaining accounts.

Start off with a five man team.
I'd have a tanking toon (top choice is Prot Pally, but Feral Druid is a strong option too), on Account A.
Whatever account is the first one in your chain.
The other four toons can be anything at all.

Once the first set get to 60th, do a good chunk of Hellfire.
You're basically upgrading the Tank on A.

Now use this tank to boost four new toons on B-C-D-E.
If you are horde, go:
01-10 Quest
10-20 ShadowFangKeep
20-45 Scarlet Monastery

If you are alliance, go:
01-10 Quest
10-16 Deadmines
16-20 Stockades
20-45 Scarlet Monastery

From 45 to 60th, a low 60's tank will not be able to instance boost.
But you can easily run the other four through quests.
In zones like: Tanaris, Searing Gorge, West/East Plaguelands, Un'Goro, Sithilus etc.
Take kill quests, skip collections.

I would get at least a PvE team and a PvP team on the five accounts.
Probably a melee team and a caster/ranged team too, which might bring you to 2, 3 or 4 teams.
Anything you might play, is a good idea to boost to 60th.

For every two toons you boost, the accounts will grant (give a free level 60) to the account one step earlier in the chain.

So if you level five toons on A-E.
And then use A to boost two toons each on B-E.
That is three toons per account, plus one extra toon on every account except E.
Normally, I'd recommend boosting four toons on B-E with A.
Which adds up to: A = 4, B = 7, C = 7, D = 6, and E = 4

Not sure if you'd want to boost four sets on the first group of five accounts...
And then four/five sets on the second set as well.

Anyway, once you're done boosting to 60th.
Level one set from 60th (or 62nd... wherever they ended up after Hellfire), as high as you can.
Ideally, it is a PvE capable team:
- Tank
- Healer (or 3x DPS that can heal in the DPS form)
- DPS for the rest.

Get the team to 80th and run some heroics.
That gets you... an 80 to boost with......
After 20-45 Scarlet Monastery, go to:
45-55 Stratholme or Scholomance
55-60 Hellfire Ramparts
60-64 Underbog
64-68 Sethekk Halls
68-80 Northrend.

It also lets you collect heroic bades and stonekeeper shards (when your faction controls Wintergrasp).
Spend 200 shards on PvP (Account Bound) shoulders, which give stats which scale with level -and- add 10% experience gained.
Spend 40 (I think, maybe 50) badges on a chest piece, which is also Account Bound and adds 10% experience.
I went for two sets... every account has.... Cloth (caster stats) shoulders/chest and Leather (melee stats) shoulders/chest.
The 20% experience bonus is two free levels you don't need to earn, for every 10 level bracket.
That is nice in Outland and extremely nice in Northrend.