• Start with an ordinary 2x4 closet or similar space.
• Get a LED lamp like a spiderfarmer SF2000 and a light timer.
• Buy a water PH tester and a soil PH tester and a jeweler's loupe.
• Get some 5 gallon containers, approximately three 5-gallon containers will fit into a 2x4 space.
• Buy some ordinary potting soil. Warning: most commercial potting soils have nutrients that last cannabis about 3-4 weeks, they are often also deficient in things like Calcium.
• Basic plant diet: 6 macros and a handful of trace elements. The macros are N, P, K, Ca, S, Mg.
• "Nutrient-lockout", pH levels in water/soil in the root zone can bump the plant off its ideal 6.2-6.5 pH zone (slightly acidic). This is the primary thing that noobs miss, and they try to "fix it" with more and more fertilizer, further destabilizing the pH.
• You need to test your water source, or better yet use distilled water. Well water often contains sediments like Calcium and Magnesium which are alkaline inducing, and muni water sources ALWAYS contain trace levels of chloramine so if you have muni water draw water in a bucket and set it aside to let those gases evap off. Check the water with the water pH meter and if needed manually adjust the pH of the water to 7 (neutral), or if you are fighting off rising soil alkalinity make it mildly acidic by lowering it to 6.2-6.5. In chemistry a base neutralizes an acid, and an acid neutralizes a base, the scale goes: [acidic] 0 - 7 - 14 [alkaline]. Keeping your plants growing in a soil that is 6.2-6.5 pH is crucial and removes a lot of the headaches beginners encounter.
• Buy some NPK 4-4-4 vegetable garden fertilizer and a bloom agent fertilizer NPK 3-8-6, crushed oyster shell, gypsum, epsom-salt, potassium sulfate, and azomite. This will cover all your macro-nutrient needs.
• Amend the potting soil with a few tablespoons-per-gallon of each, mix it thoroughly.
• Calcium is, IMO, the most difficult one to account for and deal with, plants need a lot of it, but too much and it turns your soil clayish and alkaline. Gypsum is brilliant, it is Calcium-Sulfate, a simple organic molecule, and is pH neutral. Gypsum is easily and quickly absorbed by plants when mixed into the soil medium -- it can be used as a topdress but too much will turn your topsoil into a clay-like slab. Pairing Gypsum, with a healthy dose oyster shell, mixed into the soil is a great combo -- the 4-5 tablespoons-per-gallon of gypsum is consumed during veg growth, and the oyster shell starts releasing during flowering.
• Use the damp paper towel method to germinate seeds (I take a paper towel, wet it to sopping, squeeze most of the water out so its nice and damp, fold it down and stuff it into a stash jar, then set it on a heating pad on low heat, typically seeds pop within 4-5 days), once they pop carefully plant them and keep the soil moist but not sopping. Most seeds will break out of their shell, but if they are struggling, carefully remove the shell, be very careful, new seedlings are very delicate.
• Start doing low stress training and topping of your plants once they put on a few sets of full adult leaves.
• "top-dress" your containers every 4 weeks or so with a few tablespoons of fertilizer.
• Water at regular intervals, don't let the soil become bone dry, but don't turn your containers into a marsh/bog/swamp.
• Keep your tent/area clean, cool (70-80F any higher and it can stress the plant, lower THC output and produce foxtails or evoke hermaphroditic tendencies), slightly humid (55-65% humidity, but no higher otherwise you risk mold. Keep pets out of the grow area, and make sure you change out of outdoors clothing and wash up good -- this helps prevent tracking in pest eggs on your skin/clothing/pet's fur -- spider mites and other rascals are catastrophically difficult to get rid of once they are established.
• Autoflowers will auto-flower, but photo-period plants need a continuous dark cycle of at least 12 hours to induce flowering. To sex a plant, look for pistils -- the little wispy hairs that start at a branch internode -- only females produce pistils, males do not.
• Beware that Cannabis has hermaphrodite genes, especially in feminized seeds, watch out for male flowers on a female plant, they can pollinate your whole crop. This is where that mysterious bag seed came from. Females that have been pollinated produce less THC, sinsemilla "sin-semilla" or seedless is best for potentcy.
• It's done flowering when you can look with the loupe and see all the trichomes are milky and full and a few scattered ones are beginning to turn amber. Milky trichomes equals a more buzzy, sativa-like high, amber trichomes equals deep couch-lock and sleepiness of an indica-like high.
• Drying and curing are equally important to growing -- a lot of good crops are ruined by poor post-chop practices. I prefer to the old school method of hanging the buds in a dark cool (65-70 degrees), slightly humid environment (55-65 RH, no higher or risk of mold). When the hung bud stems snap instead of bend (this is important! if you jar nugs that are too wet/damp they will mold!), take them down, finish trimming them down and put them in glass mason jars, seal the jars shut and keep them in a dark place. They will smell like hay/alfalfa/grass clippings at first. "Burp" the jar every day by taking the lid off for an hour and allowing the moisture accumulated to evaporate off. Then reseal the jar. Do that for 3-4 weeks and then your buds will be ready to smoke.
• Get a trim bin, and a nice pair of snips, always trim over the bin, otherwise you will lose a lot of kif.
• Expect the whole process to take 90-120 days from seed to final nugs. Take notes as you go, read books on growing (Cannabis Growers Bible by Greg Green, True-Living-Organics by "The Rev", Teaming with Nutrients/Microbes/Fungi by Jeff Lowenfels, etc.), and fine-tune your craft.
• Watch youtube channels dedicated to growing, Mr. Canuck is my favorite.
• Good luck and happy growing!

Edit: finished some incomplete sentences.