The button should definitely call Martinez. Limping is a huge part of the game, particularly at short to mid stacks, and if it's not being utilized, especially at lower levels, you're missing out against a lot of opponents.
I would learn what effective stacks are, I would focus on making decisions based on your opponent and the effective stack size, learning basic hand ranges (what range of hands your opponent might take an action with, and in turn, what range of hands you should take an action with knowing that information).
These are some of the important fundamentals. Don't fold too much on button NOR out of position when you're 30bb or less in HUSNG. Those are the two biggest mistakes players make.
Don't get into any static strategies, your strategy should change vs many different opponents. If you're doing the same thing vs most opponents, you're not doing it right (this is different from many forms of poker I believe, particularly full ring).
HUSNG can be very immersive and enjoyable, you just need to go into it with the right attitude and really look at different strategies and how different plays put your opponent in different situations (that they may react poorly or strongly to).