Budget Watch Collecting/Removing the movement
The first step in most watch restoration is to remove the movement. You'll need to do this for clean and lube, and it is recommended for crystal polishing, especially for non-water-resistant watches. (The last thing you want inside your watch is abrasive polish)
1. For most watches, remove the back. Screw-backs need a special tool to remove without a strong chance of damage--Luckily Indian "Jaxa-Type" removers are inexpensive. Pick the proper tips--Most watches have notches, for those use the small rectangular tips. Holes use the round tips, flats use the wedge-shaped tips with a broad flat spot. The remaining tips are "Rolex style". Don't use these unless you want to gouge the case back, you need the round Rolex rings to actually remove these backs.
Adjust the top tips to fit the wrench areas. For 6 holes or notches, adjust the top tips to fit 2 notches with 1 between. For flats, you need to pick a pair of flats about 1/3 of the circumference apart, but selected so the bottom tip hits a flat and not a point. The upper tips should be adjusted slightly small, they will spread when you tighten the bottom.
Adjust the bottom pin to fit its slot, and tighten slightly. Tighten more for flats.
Twist the tool counterclockwise.
For stubborn cases, (which includes most flats) you may need to support the case in a case clamp, and maybe support the case clamp in a sturdy vise, so you can apply downward pressure while turning. You may also want to use penetrating oil around the case as a last resort.
The other common type of watch is the snap-on. A watchmaker's case knife is best, but any sturdy or slightly sharp knife will do. Most watches have a slight wide spot to fit the knife in. Use the knife as a wedge rather than prying.
Once the back is off, there's usually a movement ring that just lifts out.
A few watches are "remove through crystal", with either a one-piece case or a glued caseback. See removing and replacing crystals.
There's an extra complication on some of these, you need to remove the stem before you can get to the usual stem release. Some will have a two-piece stem. Most two-piece have a snap fit, just pull the crown hard and even--You may want to wedge sturdy tweezers between crown and case and wiggle them off. Other two-piece stems slide apart when the slot is aligned properly--For these you might be able to see between the dial and case to get the stem slot lined up, otherwise hold the watch upside down so that if the movement comes free it will fall into your palm. Jiggle the case while slowly turning the crown. Plastic cases may have a plug at the back to access the standard stem release. Finally, some Timex one-piece cases need a special wrench to hold a flat spot on the stem while unscrewing the crown. This wrench can be made by filing a flat screwdriver or piece of brass.
Once the back is off, you will probably need to remove the stem--A few have a slot for the stem rather than a tube, these will allow the movement to lift out immediately.
If it is necessary to remove the stem, most watches release best when the stem is in the set position. Mechanical watches will usually have a button or screw near the stem. Push the button while wiggling the stem free, or loosen the screw about 1 1/2 turns, then wiggle the stem. If the stem won't come loose, slowly loosen the screw while wiggling the stem--You want to avoid completely unscrewing the screw, or you will have to remove the dial and replace the set lever.
Quartz watches will usually have a push area, but it can be hard to find. Sometimes it will be marked "push here" other times you have to experiment.
At this point the movement should be free to fall out.