I assume that you are shooting film. This is my approach when using large format, where I am using a spot meter so I can pick exactly what I want to meter from. If you're using an averaging meter you can do this but you need to be aware of the area it is averaging over. Note I'm shooting B/W film: colour materials have somewhat lower dynamic range I think. Note also I don't muck around with development for film as that's too complicated for me (remembering which sheet needs what development is something Ansel Adams could do but I'm not up to it).
- Pick the thing you want to be mid grey and take a reading from that.
- Pick the brightest highlight you care about (so perhaps the sky in your case) & meter from that;
- Pick the darkest shadow you want to see detail in and meter from that.
Note that it's perfectly fine for there to be highlights & shadows you don't care about which you expect will be flat white & black in the finished print.
If there is less than 3 stops between (1) & (2) & between (1) & (3), expose for (1): since (1) is typically the bit of the print you care most about (someone's face, say).
If there is less than 6 stops between (2) & (3), then expose for the midpoint. This will push (1) some way to one end of the useful range of the film but you will not lose detail anywhere you care about. You may want to reconsider whether you are happy to lose detail in one or more of (2) & (3) to put (1) in a better place. Typically (see below) it is better to risk highlights than shadows but remember that (1) is the bit of the print you really care about.
If there is more than 6 stops between (2) & (3) then you either will lose detail somewhere and you need to pick where that will be, or you need to reduce the dynamic range in the image: if the sky is blue then you can do this with a red filter to darken the sky, or you can use a polarising filter if you have one & know how to use it (I don't). If you do neither then it's best to expose so that the shadows retain detail as film handles overexposure better than underexposure so you will often be able to recover skies when printing but you generally won't be able to recover underexposed shadows. In any case remember that (1) is what you rally care about: if pushed you should sacrifice anything to keep (1) in a reasonable place.
(Unless (1) isn't what you care most about in the image: perhaps you are intending to make prints which are almost white or almost black: someone I know makes very beautiful prints of snow which are like this. The most important thing is to be conscious of what you want the image to look like as you take it.)