You can use keywords, color labels, pick flags, or any other searchable metadata field. There is no "best". They all work.
Click on All Photographs and then the filter bar or smart collections will allow you to do the searching and create the Portfolio.
Oh -- I see -- under text we type in the keyword and the keywords sort the images...
thanks so much, really appreciate this help!
The color labels can be assigned with a single keystroke, for example to give a photo the red color label you would press 6, so maybe that is preferable to typing in the word "Portfolio" or whatever word you choose.
and the keywords sort the images...
Just to be technically correct and use the proper terminology, this is not a "sort", the keywords "filter" the images.
If you want Lightroom to do this automatically you can create a smart collection with what ever method you choose flags,ratings ect then when ever you tag a image with your chosen method lightroom will put it in that collection.
Thanks everyone, really appreciate your kind help! Wishing you a great day and thanks again, Teri :-)