The following information will help you choose the right size lift and get the job done right -- whether you choose to do the work yourself or have it done by a professional.
Keep in mind: Even if you KNOW that you want a 3" or 4" (or larger) lift, you should always start with a small lift first and eventually work your way up. The reason is this: The faster you build, the more problems you're likely to encounter.
Building in steps allows you to work out the kinks along the way. So, your best bet is to start small, and learn to handle your vehicle in increments -- a little bit taller at a time -- rather than going for the VERY tall lift right away.
You also need to determine whether you will do the install yourself, or whether you'll leave the job to a trusted mechanic. True, there are a number of lift kits that you can bolt on right in your driveway, however you need to be realistic about the complications which could arise.
Just know that if you install the lift yourself, you will likely spend hours under your rig tweaking everything over and over again... until it is just right.
The real issues usually don't become evident until after the lift is installed when you have to get the steering, alignment, track, and everything else back to spec.
So, before you even start the install, consider how the control arms, steering linkage, slip yoke, drive shaft length, U-joint angle, brake lines, gearing, braking and axle strength will all be affected by the vehicle's new height.
Some things you should know straight up: If you're going for a larger lift (3" plus), then you will most likely need longer lower control arms and longer shocks. You will also need to lengthen the front and rear brake lines. If you lift 4" or more, then you will need longer upper control arms as well. Plus, you will want a longer trackbar, and you might need to add longer emergency brake lines.
NOTE: If you tend to do a lot of offroading and you still are uncertain about which type of lift you really need or want, or you think you want more than a body lift can provide, then check out this great article which explains the different types of lifts -- from spring over axle, to shackle reverse, coil suspensions, lifted springs, shackles and body lift: The Truth About Lifts