A lot of people find a "sweet spot" easily or early on, so hammocks become enjoyable quickly. I wish I could say the same is true for everyone. Personally, I went through a challenging phase during the winter when I struggled to figure out the warmth bit. Getting the "knack" is part of the allure for some people. I guess what I'm trying to say is that it is okay if hammocks don't work for you. If you find in the end that your body doesn't work in a hammock, don't worry about it too much. Your warbonnet has a high resale value.
That said, let me see if I can give you a few things that may help. Knowing your height and weight will help a little, but let's rule out a few basics.
Getting a near perfect flat lay in a hammock is the key to a good sleep. Laying off center in a hammock (aka the diagonal) usually drops you into the sweet spot, but that depends on the length and width of the hammock and how deep the hammock is hung (the sag).
I am preparing a new illustration that clarifies the relationship between hammock size and the appropriate sag to get a flat lay in a hammock. In a nut, the wider and longer the hammock, the deeper you can sag it to get a diagonal lay. Small, narrower hammocks (e.g. GT Nano 7) must be hung with a shallow sag in order to get a comfortable, flat lay. In fact, if the hammock is wide enough, you could hang it in a "U" shape (really deep) and sleep perpendicular to the attach points and get the flattest lay possible.
This new discovery goes against the standard "30°" rule we often cite as the "golden rule" for hammock hang. Hammocks with fixed ridge lines attempt to set the sag permanently for that hammock, but you may find that adjusting the length of the ridge line (and therefor the sag) will change the lay and may give you the right lay you are looking for.
Some people get sore backs and shoulders from getting squeezed by the hammock. Shoulder squeeze is common and is usually a result of having the wrong sag for the hammock resulting in an improper lay.
To fix head strain, you may also try using a neck pillow that fits under the nape of your neck. I find this style more comfortable than no pillow, and better than a regular pillow that kinks my neck too much.
One last caveat: I've observed that those people with the worst experiences in hammocks are best helped in person. Sometimes the descriptions make the most sense when seen in real life. Most of the folks on HF would be glad to demo and group hangs or boy scout camporees where hangers will be present.