What do you have to do as far as prep before you reload and how often do you have to do it? Do you have to resize after every shot? I am new to reloading and will try my first loads this week.

Resizing must be done after every firing.

Here is the order that I follow for bottle necked cartridges:

Lube cases, place in loading block
Run cases through sizing die. I will partially full length size for most of my reloads for centerfire rifle. This basically brings the neck back to dimensions to hold a new bullet, and sets the neck back just a little bit. I do this only for brass that has already been fired in that particular firearm. If it is new brass, or brass which has been fired in another firearm, or brass for an automatic, I will full length resize.
Next, I check the length of each case with a micrometer to make sure they are within specs. If not, or very close (within about .001-.002"), then I trim all the cases from that batch to get me .010" below max length.
Then, I chamfer and deburr each case to allow the bullet to go into the case neck easier.
After that, it is priming with my RCBS hand prime tool. There is one that came with the Rockchucker, but it is one where there are a lot of primers in a tube, and you use the ram, which I didn't like, and bought the hand prime tool.
Then, it is weighing the charges, and seating the bullet.

Now, these are pretty basic steps of what I do. Most reloading manuals will have more detailed instructions. I have the Lee #2 manual, which I like, along with a couple of others, and information I get from powder and bullet manufacturers. Lyman is a good one that I hear, but I don't own.

Good luck!!

Charlie is right on the money here......if I may add 2 things to just try and break it down further.

#1 when you lube cases, only lube about the bottom 2/3 of the casing if you get lube up onto the shoulder you will see dimples. (I made this mistake before) and WIPE THEM OFF WHEN YOU ARE DONE!!!! (it will be messy)

#2 to expand on the resizing process, when you fire the round, the casing expands to fit the chamber of that particular rifle, if you are sure that you are using the same casings in the same guns, just partial full length resize....this can be done by....

insert casing into shell holder, run casing all of the way to the up position.
screw die down until it touches.
then back it up 1 full turn.
I know the instructions say to take the die down 1 full turn, but you will full length resizing if you do that, turning it up 1 full turn will allow you to not touch the body of the casing.

if you run into any troubles ask more questions, I know I sure did when I started!!!!!

if you have a bolt rifle that will be firing these rounds and not another gun or multiple guns then you can get away with neck sizing only... resizing the neck of the case, the area that holds the bullet... you never touch the shoulder or further back...

if you are using a lever, auto, pump, etc you MUST full length resize in order to get proper and consistant feeding.. these guns need the extra elbow room to get that round in chamber properly... do not OVER lube.. you'll collapse and dimple the shoulders

neck sizing is "generally" more accurate thatn FL sizing, especially if your chamber happens to be a good bit larger than SAMMI standards for the case dimensions which dies are manufactured to...

you can get more indepth but this is the meat and potatos of it...

A step that I always use is to clean the primer pockets thoroughly with a proper brush, plus the flash hole prior to seating the primers. This ensures the new primer seats fully and the flame ignites the powder charge well.
Also, holding the neck and shoulder of a fired casing in the flame of a match or candle will put smoke or soot on it. I then run that case into the backed-off resize dieand gradually lower it until it just barely removes the soot from the shoulder of the case. This resizes the case for your particular rifle.

IF you reload a case for use in the same gun it was just fired in, often you can get away with just partially resizing , squeezing down about 1/3 of the case neck, just enough to give a firm grip on the new bullet when it is seated. After a number of shots, you MAY find it necessary to fully resize a batch of cases, if they start to be come difficult to rechamber in the gun. This depends a lot on how hot you load them-the hotter the reload, the sooner you'll have to do this.

I have a couple of very light reloads using cast bullets for plinking and target practice that develop such low pressures that the case necks don't expand upon firing. I can reload these without having to resize even the the necks.

Make sure to trim your cases when they start to exceed the maximum case length. This is a very important part of case preparation in order to avoid excessive pressures which can result if the case mouth is jammed into the chamber throat, making it difficult for the case mouthto easily release the bullet.

Well you will get a lot of ways of doing things when it comes to case prep, but most of the main things are covered. When I changed from full length sizing to using a collet die my groups instantly shrunk. Now when I shoot a hand full of test loads I check the cases over and wipe them with a bit of alcohol to remove any dirt and run them through the collet. The I clean the primer hole completely clean and check for trimming. Some times I may run them in the tumber but very seldom as thery just came out of my rifle and have not been thrown around on the ground. Then new primers, powder and bullets and away I go again. The collet die has saved me abunch of time and the rounds are a lot better.