Hello and welcome to the forum
This is the introduce yourself section, if you have questions ask them in the relevant section, not many people read the introduction part so not many people will see your questions, I suggest you ask these questions in the sick plant section and in detail explain how you are growing your plant, soil, hydro etc, what lights, temps, humidity, nutrients, how much and how often, we work on your information you give us, if you dont give us clue's, we wont be able to answer you
You cannot increase a plants THC, it is pre destined by strain, all you can do is grow a plant as best you can, and thats all, a poor grown plant will produce less bud and Trichomes than a plant grown optimally, some strains of plant produce prolific amounts of Trichicomes and some only a 1/4 that amount, but the mass of Trichomes could be less potent than the plant producing 1/4 the Trichicomes, so the lesser Trichomes can and often is far more potent than the plant with a mass of Trichomes (crystals).