Do a LOT of searching...there is a TON of information on first gens...depending on how much you know (or don't know):
You can raise the height of your truck many ways...here is a post I made in another thread:
You can search and find all sorts of good info on this...here are some good links:
My PML HOw To is in my signature
I have been a fan of Automotive Customizers at 4x4parts.com
Upper control arms and new Cam bolts are mandatory for the front end beyond 1-1.5" of lift. AC has the UCAs with an idler arm brace ... and Cam bolts which come to ~$500 when all is said and done.
You can get the 3 leaf add a leaf pack for around $200 if I recall correctly. That should lift your rear up 3 inches according to their website. Leaf packs add stiffness to your rear, so the ride may be a bit harsh. Avoid the single leaf add a leaf, as it is very stiff, and will make your hard much harsher than a 3 leaf pack (made this mistake on my old Tacoma). The leaf packs are nice if your truck is heavily loaded or are trailering things. Leaf springs are notoriously known for not being precise as far as the amount of lift it gives. They are springs, so depending on the weight, cargo, etc they may be high or low, and will sag in time.
When the leaf packs start to sag, you can get lift shackles (+ 1.5") for $65 to boost them up a little bit more.
If you want to avoid adding a leaf pack, and a potentially harsher ride, like me, I went the shackle only route for the rear, but I got the Adjustable Shackles, which have a maximum lift setting of 2 1/8", which is a bit more than the regular lift shackle (1.5"), but still maintaining the stock ride quality. I paired that with UCA's to match the lift in the front.
If you are a Poor Man, your Lift is the PML. Your stock UCAs can be adjusted to give you ~1-1.5" of lift, which you can pair with the 65 dollar shackles. Your front end will be maxed out, and you have to be careful of alignment issues.
Keep in mind, all of this is suspension lift. This means you are trading downward tire travel for upward tire travel. This means that you can't get larger tires than a stock X, as once the suspension is flexed, they will hit whatever they would have hit without the lift.
You can piece together a 2" body lift as others have mentioned, which raise the body 2 inches off of the frame. Since this raises the body relative to the frame, you now have room for bigger tires (33")
Also, on a stock 2003 X, you can fit 32" tires (265/75/16) with just trimming a little bit of plastic in the fender well (non visible plastic, body/fender/trim still looks stock)
Note: None of this includes new shocks. To maximize the usefulness of your lift, you should get shocks made for an X with a 3" lift...and REMOVE YOUR REAR SWAY BAR!
So, In Summary Pick a Suspension Lift, a Body Lift, and a Tire Size:
3" Lift to Suspension
3 Leaf pack and UCAs: ~$700
2 1/8" Lift to Suspension
Adjustable shackle and UCAs: ~$600
1-1.5" Lift to Suspension
Lift shackles: ~$65
2" Lift to Body
AC body lift kit for ~$225
Piece your own together for ~$70
Lift due to Tires
1/2" lift with 32" tires (No Body Lift)
1" lift with 33" tires (with Body Lift)
Beyond these, you are getting into solid axle swaps, sawzalling your fenders to shreds, and putting on 37" tires...which = $$$$$ and a potentially destroyed truck if not done right.