I only do studio work which is why I was asking about how much power for these shots - I've been interested in venturing outside for a while
As a result I've no direct tips for outdoor work but as I mentioned in my own post I swear by using a light meter for working with strobes - it just makes everything so much more predictable and accurate. You can work from a histogram if you like but why waste so many shots trying to get the exposure right - I like to nail it quickly and then interact with the model. It also lets them know you're in control and know what you're doing which give a good impression of professionalism
I have four strobes in the studio I use but I often just use a speedlight to rimlight or add hairlights to the model - for this application there's very little power needed. The only thing to watch out for is the speedlight can be a little blue so adding a warm up gel can be necessary.