This may seem like a lot of work but it is the best way to ensure a top quality finish that will last for years to come with no issues. You can cut corners but there is a good chance you will have issues down the road.

Vacuum and dust all surfaces first so you are not just mushing dust into crevices. Clean cabinets with a mild detergent and warm water. Use a damp(not soaking wet) rag. Do another wipe down with clean warm water to remove any residue. If you have previously used any kind of polish with oils or silicone you will want to wipe down with a de-greaser to break up any oil/silicone particles that the soap and water do not take off. Even if you haven't used any products previously this is still a good idea because surfaces get oils on them from cooking and handling with bare hands. There are many all natural based products out there. Next you want to de-gloss(break the surface) of existing finish. This can be accomplished by using a combination of 220-320 grit sandpaper,burgundy scotch-brite pads for details, and Wil-bind(Surface preparation) Use an old toothbrush , q-tips and toothpicks to get in the nooks and crannies if needed. Try not too sand so hard that you go to raw wood.

For a base coat you want to use a shellac based primer such as Zinsser or similar. It comes in white but can be tinted if using a darker topcoat. After primer inspect for any defects that need to be puttied or caulked. Let caulk and putty fully dry then scuff the surface with a 220-320 grit sandpaper and scotch-brite to sand down any high spots and smooth out surface. (((IMPORTANT: DO NOT caulk the gap or build up paint in the gaps between panels and the frames of doors if you have solid wood doors. Wood expands and contracts with humidity and when the panels move the caulk line or paint build up will crack and flake off later looking really bad))) When scuff sanding, if you happen to burn through the primer while doing this make sure to touch up these areas before going to topcoat, or you will have adhesion issues and a rougher final finished surface.

If doing the finish yourself an oil based paint should be used. Latex is ok but is not as durable in the kitchen. Buy the best you can afford. Paint materials is NOT an area where you want to cut corners. Actually the best oil based product would be an exterior grade which has anti-mildew and other additives that will protect it from UV exposure and moisture although an interior grade will do as long as your kitchen is not too steamy and you clean up any spills that may occur.The topcoat should be applied in two coats using an oil based paint. The minimum sheen of eggshell should be used for long term protection and durability. The lower the gloss that is used means there are more flattening agents added. Flattening agents make the surface more porous and open to staining and wear at a faster rate then the higher sheens.

Just as when doing any work or using chemicals make sure to wear protective eye wear, gloves and a respirator and provide plenty of ventilation. You should always start somewhere that is not easily seen like the back of a drawer front so you can make sure you are happy with the results of every step.

Like any paint finish DO NOT use any type of chemical cleaner for maintaining it.This will break down finish and cause discoloration, streaks and possible physical damage to paint. A dry wipe and occasional dusting is all that is needed for regular maintenance. Wipe up any spills immediately with a clean cotton cloth. If needed, you can occasionally use a very light duty liquid soap in warm water with a slightly damp cotton cloth followed immediately with a dry wipe to prevent streaks.

Keep your left over paint in a sealed container and keep in a cool dark place to do any touch ups when needed.

Hmmm can not seem to figure out how to link a web page. Copy/pate these for products mentioned

Wil-bond
http://www.ipaint.us/wilbondquart.html

Zinser
http://www.zinsser.com/product_detail.asp?ProductID=10

Wow! Thanks Kitchendesigner! Yes it does sound like a lot of work but I knew it would be. After seeing all the transformations on this website I can't wait to get it finished. The hardest part is starting it!

I hope you don't mind being able to see grain through the paint--oak often leaves the grain texture visible through paint. I love the look, but some people want a slick grain-free look and are disappointed.

Be sure to take before and after pictures. Have fun!

If you don't want to see the grain through the paint, you just have a lot more work to do, but it can be done. I've been researching this issue quite a bit lately too; when the weather warms up we're going to start painting our oak cabinets. Look for nodirthere's kitchen, and she gives instructions on how her painter got a flat finish (no grain) out of her painted oak cabinets. I'm not sure I can live with the grain peeking through, so I think we're in for the long haul. There are also some instructions from This Old House on painting cabinets that sounds helpful:

Here is a link that might be useful: This Old House - painting cabinets

We have started this project and we have oak cabinets. My husband is spraying them, he is using Benjamin Moore Underbody primer. He has put 3 coats on the doors, he is going to sand them then apply another coat. This primer is excellent, he has sanded one so far and it looks like it will be really smooth once he applies another coat of primer. I will let you know how it turns out, hopefully this weekend. It is going really slow because he is spraying in the garage and it has been so cold.

I suggest getting a random orbital sander - can get a decent one for ~$50-70 - and sand, sand, sand. It really does make the work easier & you can use for all your future refinishing projects! Not that you have to get down to bare wood or anything, but just to break that hard surface + get rid of all the crud on the surface. The prep work for something like this reallyis a good 9/10 of the job, the painting part is a breeze relatively speaking although you do have to pay attention to technique and quality of materials as mentioned above.

I spent 3 week filling the "grain" on my oak cabinets with wood putty and sanding it off - repeat, repeat, repeat. 3 coats (sanded between) of Zinzer primer, 4 coats (sanded) of latex epoxy paint and my finish is like glass! 2 years later and they are still perfect :-)

It is possible to eliminate the grain on your oak cabinets - it just takes patience and a LOT of sanding!!

One of the best things I did though was realize I didn't really like my cabinet doors and to by new doors/drawer fronts in a pre-primed paint grade maple. The new fronts really made our kitchen look brand new and saved me another 2 months of work (it took 2 months working every day to refinish the cabinets and paint the new doors). This was surprising reasonable for the change it made and is the thing that made me most glad we decided to paint our cabinets instead of replacing them!