Selecting areas in PS. ***UDATED***

Some results:

More here: http://smg.photobucket​.com …sGuy/Samples%20​-%20Rides/

A lot of advanced post processing procedures in PS require a selection to be made, so that you can work with just a part of an image. Filter>Extract works well if there's a lot of fine detail like hair or weeds that you need to select, but most of the time I'm working with something that has hard, well defined edges, so...

My favorite selection tool is the Polygonal Lasso Tool, because it's precise & it only anchors when you click. (If the phone rings, you can just leave the mouse where it is & pick up the process where you left off 3 hours later.)
So, click, release, (NOT click & drag), move, click again... 'till you're done. If you click in a wrong spot, hit 'Del', NOT 'Esc', & the last anchor point will be removed.
Set it at 1-2 pixels Feather; I usually use 1 on 'full' sized 6MP TIFFs. If you're working with low res JPEGs, your "results will differ" as they say in the disclaimers!

The first secret, if there one, is that a curve is simply a series of straight lines if you blow it up large enough, which is why I like this tool - you don't have to painfully follow a curve exactly while holding the mouse button down.
So, the 2nd secret is to make the pic BIG. No, BIGGER that that! Try 300% for a 'full' sized 6MP TIFF. You want to see the distribution of pixels along the edge & I draw the selection just inside of the outside edge.
If you 'run out of' pic, & need to move to a fresh area with it, just nudge the pic border & PS will scroll to the new area of the pic. Or, as Scottes said, "If you run out of picture and need to scroll around, just hold down the spacebar. The Polygonal Lasso Tool will temporarily change to a Hand icon, and you can click and drag the pic around. Let go of the spacebar and you're back to the Polygonal Lasso Tool where you left off.", but I still prefer to just nudge the pic border. Everyone has their own way to do things PS gives you a lot of options to customize your workflow.

Sometimes you can "lose your place" & not be sure whether you need to include or exclude a part of the image. CTRL (plus) + will increase the magnification. CTRL (plus) - will...
CTRL + Shift (plus) + will giver you bigger jumps.

I like to Hit F twice & TAB once to get a bigger screen to work with. Try it. These are just toggles & hitting F & Tab again will take you back to the screen you started with.

3rd "secret":
For very dark areas that tend to blend in together...

1. Make an Layer> New Adjustment Layer / Levels.
[The beauty of these is that changes aren't permanent since PS remember the inputs and holding ALT (makes Cancel change to RESET) & clicking on the Cancel button will let you go right back to the original zero settings. Or, you can just drag the sliders to the new settings that you want to use.]

2. Drag the middle slider to the left to brighten up the dark areas. I usually start with this.
3. Select the bottom dark areas. I usually close the selection & save it to a Channel. Click on the Channels Tab, & click on the 'Save selection' button at the bottom
When you've done that, then you can turn the 'eye' off on the Adjustment Layer if you're done with it, or...

Then, for very bright areas that tend to have little detail...
4. Double click on the Adjustment Layer to open it, or hit CTRL+ALT+L (= Levels with last settings). Reset it so the bright areas have some detail & separation from the background.
NOTE: DO NOT HIT CTRL+ALT+L IF AN ADJUSTMENT LAYER IS NOT PRESENT! That will run Auto Levels, & you might not notice that happen.
5. Hold down Shift & start selecting the bright areas to add them to the previous selection. You don't have to hold Shift after the first click. (If you screw up & the previous selection disappears, goto the Select menu & Recall the selection. Or Shift+CTRL+D). Or use the selection channel you saved to recall the selection.

6. Double click on the Adjustment Layer & Reset it to 'zero' (the original settings). Or you can just drag it to the Trashcan. Or you can turn the 'eye' off on the Adjustment Layer & just leave it there for later use.
7. Shift- click to start adding the 'normal' areas to the other selections.

When the selection is OK, hit F once & TAB once to get back to your 'normal' PS screen if you used them before Step 1.
The NEXT thing you MUST do (trust me on this) is to click on the Channels Tab, & click on the 'Save selection' button at the bottom again.

Remember, after you've made the primary selection, you may want to modify it.
SUBTRACT from a selection by holding down ALT 'till you click inside the previous selection, then you can release ALT & continue clicking.
ADD to the selection by holding down SHIFT 'till you click OUTside the selection in the pic, then you can release SHIFT & continue with the selection.

After a while, you'll be able to make a complex selection in about 5 minutes - not as fast as the 'automatic' selection tools, but you won't have to spend time cleaning up the 'automatic' mistakes, either.

I hope you have no problems with this, but if you find misTeaKs, let me know!

There are more links, including more complex extraction methods using both PS & free software in this thread:
Mustang & B-17 + PS

EDIT: Now that you have a saved selection, where do you go from there?
Using selections with a Layer Mask to change a background. Again, this works best with "non-hairy" objects like cars, but it will illustrate using a Layer Mask.

There's some screenshots of the Palettes in this thread: Some shots of Jim's '68 AMX and in Post #5 in this one: '83 Camaro Z28 Pro Street 502 Part #1

EDIT: And it's nice to have something worth the time you spend on this, so here's some ideas on "A few Car Lighting Tips"

EDIT-2:
More on "1. Make an Layer> New Adjustment Layer / Levels." above: Adjustment Layers are great for making local changes when you only need to adjust part of an image:
Airport runway shoot

See post #14 & 15 of larsj53's 75 Chevy Laguna S-3

And see post #13 in this, & the links in it.
Malibu in the snow.

More on Layer Masks in post #31, below.

All the ways to mask in PS:
A Comprehensive Introduction to Photoshop Selection Techniques - Psdtuts+ is excellent!

Luminosity Masks

A more complex method where you have trees or hair in the image...
Russell Brown Tips & Techniques: Advanced Masking
Look for "CS5: A Crazy Advanced Masking Solution to a Really Challenging Project" & others.
The advanced tut video: http://av.adobe.com/ru​ssellbrown/ExtractSM.m​ov

Tricky Cut Outs made EASY and FAST: PHOTOSHOP #76 (Leaves, hair...)
https://youtu.be/myecP​HJ8Iwo

The improved Refine Edges tool in CS5: PS help with combining multiple images ...

Help with Refine Edge in PS

EDIT-3: Clone Tool
Sometimes the clone tool is easier to work with if you make a selection first where there is a sharp border between colors. There I've found that it's easier to select an area & clone within it to keep the colors from mixing.
https://photography-on-the.net …showthread.php?​p=16972291
https://photography-on-the.net …hp?p=7673809&po​stcount=11