The problem with tutorials are everybody has a different starting point.
Some people have multiple drives or partitions already. Some people have
only one drive and no partitions. This makes a big difference in how drives
are designated by Linux and where you put things. One person may want to
put it on sda and another on sdb or sda2 on one machine may be different
from sda2 on another. Also it depends on which version of Windows you are
using because W7 is spread across two partitions and also some
manufacturers have a restore partition. So the chances of anybody having a
similar setup diminish rapidly. If you blindly follow them without
understanding then you can royally mess things up.

The second problem with online tutorials is that some are very dated, using
versions that are no longer available. Canonical has changed Ubiquity
(installer) much over the years and the wording may change and options that
were once there have disappeared. For example a custom installation was
once referred to as Manual or custom, but is now called Something else.

Use any tutorial or guide with caution. That being said, this is a very
routine procedure.

Here is a great guide on how to install Kubuntu 12.04 NOT sharing with
Windows.

www.howtoforge.com/...erfect-desktop-kubuntu-12.04

This is a tutorial on dual booting Windows 7 and Mint

www.howtoforge.com/dualbooting-windows-7-and-linux-mint-12

You will notice when comparing the two that the installers differ. You will
want to do a Manual installation. It is probably better to do the
partitioning ahead of time, but that is my personal preference. You should
plan what you want the final partition table to look like.

Rules of thumb: Keep Windows first with other partitions going after it.
Shrink your Windows user partition to make room for other partitions. Linux
will need at least two partitions, one for the OS and a small SWAP
partition. (If you are up to it then go for three with the extra being for
home).

This is where it gets complicated. Let's assume that your computer has
three partitions already (C: for the OS, D: for System and a Restore
partition from the OEM) then you can make only one more primary partition
(maximum of 4). The way around it is to make an Extended Partition with
your Linux partitions created inside of it. This makes for extra work and
room for error. That is why you need to scout out your own system first and
plan accordingly, rather than following a tutorial made for a different
system.

I don't want to make this sound scary. It isn't. There just is no way to
give a tutorial for every possibility. It is better to learn a bit and work
generally. The easiest route is to add a second drive (they can be cheap)
and use the whole drive. It won't touch Windows on the other drive (so long
as you know them apart). and it will set-up its own partitioning scheme on
the second drive.