Strength Training
I am fairly flexible on the approach to strength training but do endorse the little and often and primal movements. For example if you have easy access to a pull up bar and would normally do a session with 5 x 4 pulls ups you would do 20 pull ups, if you go past it 10 times a day and do 2 pull ups every time you have done 20 pull ups without a session.
The primal movements, as per Primal Endurance are: Push up, pull up, plank and squat. Aim to integrate these into your daily routine. As with running and any exercise routine the best strength training routine is the one you are going to do consistently.
In terms of reps / sets, again the experts I have heard have said the best exercise is the exercise you will do. So if you like low weight / bodyweight and higher reps then do that, if you like high weight and lower reps / sets then do that.
In actual strength training sessions I recommend a combination of the following:
Legs:
Calf Raises
Heel Drops
Toe walking
Squats - bodyweight and weighted
Lunges
Box Jumps or step ups
Single leg balances
Resistance bands - I like doing seat leg rises, from bent to straight leg to work the quad. I like these for hips work and these for quads and sometimes arm work. Great for cheeky strength training whilst in meetings.
Banded slow running movements - mimic running movements with the bands for resistance.
Core:
Planks - There are many variations.
Crunches (done correctly)
Hip Thrusts (can be weighted)
Standing Crunches
Standing Russian Twist (weighted)
Arms
Push Ups
Pull Ups
Bicep Curls
Tricep Dips
Upright rows rows
If you have barbells then deadlifts are great to add in as well.
Any exercise that mimic good running form are fantastic but the overall goal of strength training is to maintain muscle mass for longevity and to reduce injury risk...and ideally improve performance.