It think the question has been answered multiple times,
Great courses have been shared, good advice has been shared, the only thing missing is the practice and only you can provide that.
My advice when creating a basic human base mesh is to stick to all quads wherever possible, if you need them only use them away from joints. Back of the hand, forearm for example. For joints use a minimum of 3 edges loops, for an elbow joint for example, one edge loop around the centre of the joint and one either side. Much like adding holding edges on a hard surface model. Same goes for all other joints.
The number of vertices is not precise, the number you need depends on the level of detail you want to add, the size of the human you are creating and what you feel is enough for the models purpose.
You can start a human, or any character however you like, you can use reference images and use vertex modeling, basically adding vertices outlining the reference and building up from there. You can use default objects to block out your character first and use retopology techniques to gradually refine the shape. A good and fairly easy technique is to use the skin modifier, the skin modifier plus a subdiv modifier allows you to add one vertex at each joint and another in between where you want to add more shaping of muscle areas such as biceps and calf muscles. Applying the skin modifier and the subdiv modifier gives a pretty good base mesh to refine where needed, joints for example.
There are many techniques, often several techniques can be combined. That’s where practice comes in, to find the right technique for you.
As already mentioned, no single video or course is going to give you the result you desire, again with practice, the result you desire will come from you.