Welcome! Don't freak here is a list of some do's and don'ts:
Part 1 Contributed by: Bongaloid
Part 2 : Bush_Grower
First time growers frequently:
Overwater their medium based plants. When you pot your plant, judge its weight dry by hefting. Then, water the plant thoroughly, until water runs through the drain holes. Heft it again. When your pot feels as nearly as light as it did dry, its time to water again. Overfeed their plants. As MrSoul says, beginners rarely under do anything. When all else fails, follow the directions on the fertilizer bottle. [Editor's note: dont follow GH's instructions! Use @ 1/4 their recommended strength, or follow recipes in the FAQ]
Overanalyze their grow. A first grow is like a first born child: you pay attention to every little thing that happens. Further, you worry at the first sign something may be wrong. Pay attention to what happens in your grow, but do not try and find a remedy for every yellow leaf. Frequently, the remedy of flushing your medium causes more problems than it solves. Be responsive when things go wrong, but be conservative in your remedies.
Overspend on grow supplies. New growers frequently commit themselves to unrealistic and expensive first grows. It is much more efficient to learn to grow and then invest in high end equipment rather than the other way around. Most experienced growers don't have room for all of the grow paraphernalia they aren't using. As you will see throughout this FAQ: K-I-S-S.
Overpost. Try the search engine first. Chances are good that any question you can think of has been asked and answered before.
Talk about their grow. Don't tell anybody that does not have to know. How can you expect anybody else to keep a secret that you cannot.
Part 2:
Contributed by: Bush_Grower
1. Don't Overwater
Overwatering kills marijuana plants. Water once the top few inches of the soil dries out.
Hydroponics is harder to over-water than soil, due to the abundance of water roots.
2. Don't Tell People
Why? They will only be jealous. People love to feel important and that is why they will tell other people; because others will listen to them.
Keep it to yourself.
3. Touch/kill Germinating Seeds
It can take up to 10 days for a seed to sprout. The paper towel method is not recommended because you must handle the seeds when transferring them from the paper towel to your growing medium.
4. Grow seeds from seeded marijuana (hermaphrodite seeds)
Unless you are prepared for possible disappointments don’t use "unknown" seeds. This is why people buy seeds from seedbanks.
Self-seeding MJ is produced from hermaphrodite plants or a very stunted and late flowering male the grower did not notice. Flowered hermi seeds will produce tall late flowering females coupled with early flowering males.
5. Don't Over-fertilize
Fertilize after first 2 spiked leaves appear.
Start with 25% of recommended label strengths and work your way up. If the leaves suddenly twist or fold under, Leach and Spray with pure water for several days!
Don’t fertilize your plants every time you water! (Soil)
A common watering schedule is to fertilize at full strength, then water at half or quarter strength. This prevents excess salt buildup, leaf and root burn. In addition, don’t water at full strength if the medium is too dry – root burn can occur.
As a precaution, leach the plants with lots of pure water every 2-4 weeks.
6. Don't Under-fertilize
Under-fertilizing is less common. If you prefer to give the plant ‘just enough nutrients’, use a organic soil mixture with blood meal and bone meal or some slow release fertilizer with micro nutrients.
7. Don't Start with Clones
Start with seeds. Bugs are a pain, as are plant diseases. Many growers are able to grow indoors without pest problems for years. Another grower’s cuttings are almost guaranteed to have diseases &/or pests.
8. Don't Provide A Bad Environment
Always provide air circulation and fresh air even during the night cycle. All the air indoors should be replaced every 5-10 minutes.
Humidity between 30-70% temp aim for around 75-85' Even seedlings need a gentle fan to strengthen the stems.
9. Don't Harvest Too Early
25% of the weight will form in the last 2 weeks. Begin flushing with 100% pH’d water when the pistil are 25% brown. Harvest when the plants have totally stopped growing and the white pistils are at least 50-75% brown.
*NOTE: Outdoors if security is a factor make your own call on when to sacrifice the fields. Also take buds continuously in case of thieves.
Common questions:
Q. Can marijuana grow in a northern climate?
Marijuana plants can grow anywhere corn can grow. All it needs is three growing months - seed to harvest. 2 if started indoors!
Q. Why do I have to buy seeds? Why can't I use my own that I picked from my own stash?
Most people desire, and want to be guaranteed, certain characteristics in their mature female plants. The seeds from any weed will all grow into something different. This is unprofitable and inefficient. As opposed to knowing the single set of requirements for your entire crop, you must provide a different set of requirements for each of your plants.
Q. What is better for a new grower - hydroponics or soil?
I believe the all around "better", more convenient setup is soil. Hydro makes plants grow faster, but won't make your buds more potent than soil. Hydro should be attempted after you have a few successful soil crops under your belt.
If you are starting from seed and growing for personal, soil is the practical growing medium. If the crop is started with clones and is commercial, a hydroponics setup is more practical.
Q. Why are my seedlings stretching?
Low light conditions. They also need a gentle wind. Plants will also stretch when subjected to conditions of high humidity.
Q. What kind of lights should I use?
Cheap 4 ft. cool white fluorescent tubes : for germination/seedlings
400 watt Metal halide/HPS : for personal home growers
1000 watt Metal halide/HPS : for some personal growers and commercial growers.
*Use at least 40 watts per sq. foot of grow space.
Q. How far should the lights be from the plants?
Fluorescent: tips of leaves almost touching bulbs
400 watt halide : two feet away from seedlings and one foot away from grown plants
1000 watt halide: four feet away from seedlings and two feet away from grown plants
I am new to growing I have never done this before nor have I ever see it done. I have smoked for YEARS but have been pretty sheltered (I guess you could say) from the details as to how it got to me. I have been doing lots of research here and other places for help. I live in Texas and I'll be growing Pakalolo & White Lady I have heard that this should be easy for me to start out with. I just ordered the seeds online and btw I'm scared to death. 
I plan to grow indoors in soil however, I have limited space so any ideas would be nice. I have been looking at lots of your setups and they are VERY nice I don't think mine will be as nice. Anywoo, I'll let you guys know when I get them in b/c I'm sure I'll be freaking out. 
However, I'm not tell anyone I really don't run in a circle that would care anything about it, that is why I'm growing my own. I buy a hole lot tho do you think that will help? Now I"m scared. OMGOSH!!!
