Perhaps it is easily recognisable as to which somatotype you belong to, which is great as you have your starting block. Work from there and see where it gets you. Sometimes however it’s a little more tricky than that. More often than not, people turn out to be a combination of a couple of different types or sub-ranges. So for example a Mesomorph might have some Endomorphic qualities such as stubborn inability to shift fat. Likewise, another Mesomorph might have some Ectomorphic qualities, such as losing too much muscle if they undertake too much cardio. (It should be noted that Endomorphs and Ectomorphs never cross over with regards to the qualities, they are polar opposites).
What is needed here is a bit of experimentation. You will have a general idea of which body type the majority of your traits align with. You may need to eat more of a certain food, be it carbs or fats if you are trying to put on weight. You may need to undertake more cardio or increased reps with weight training. Play around, and make a note of what works. The key is in finding the balance in what works specifically for you, there is no right or wrong here. Years ago (as an Endomorph myself) I found that by undertaking sprints on a regular basis I was able to drop weight much more rapidly than undertaking steady-state cardio. I had been undertaking steady-state cardio for years and never had the dramatic weight loss results from it that I did with regular sprint drills! If only I had experimented earlier!!
Choosing a workout and dietary strategy for weight loss/weight gain very much depends on your body type and what you have to work with. For the most part, we don’t have a say in this, genetics are genetics, and we have to play the hand we are dealt.
Identify your core somatotype and find your starting place for the best way to effectively tailor your diet and exercise routines. Although we cannot change our somatotypes or genetic buildup, by taking effective measures we can optimise our training, diets and lifestyle to bend the rules in our favour.