Hey Hanno,
I'm no expert or anything, but I'm halfway through my first grow and I've learned quite a bit so far. SO some advice to avoid the mistakes I've made.
Invest in enough equipment so you know what is going on with your plants and keep records of what you do when. It's incredibly hard for people to help you online when you don't know what your PH is, temps are, humidity is, nutrients are. Also, when did you water? How much did you water? Keep track of this stuff. Start a grow journal on this website and write it down there. Put a link to it in your signature. Then people can find out about the history of your grow and give you better advice.
1. Be patient! This is a 6 month journey you are embarking on. You may get some great bud out of it. You may get nothing. Its the only way to learn though.
2. Mylar -
$13 online Don't use tinfoil. Get this stuff if you are going to grow inside for a bit. Or just stick with white walls. That works too.
3. Temps/Humidity -
$10 at Target This thing will record the min/max temp and the min/max humidity of your grow area.
4. PH -
$5 at hardware I notice these things everywhere I go now. It's good for 10 tests of your soil and water and it worked for me. There are home ingredient solutions to raise and lower PH.
5. Moisture meter -
$5 at hardware Does what it says. You can see how moist/dry your soil is at the bottom of your container.
6. Nutrients -
$30-40 at ? I found mine at Longs Drugs for $30. Get these, follow
the chart. It makes it easy for you and takes out a lot of the guess work. Chances are you won't over fertilize them either.
7. Misc. Get a oscilating fan if your going to keep them inside to make the stems strong, cycle the air and keep away molds. Also, get big enough pots (3 to 5 gal), keep a close eye on them for pests if you are growing outside and be ready to react to pests immediately (already have your solution in hand.)
8. And read the crap out of this website. There is a lot of good info in the GrowFAQ. Make sure to look there before you post. And don't trust everything everyone tells you. People mean well, but it's just hard to know when you can't see, touch, live with the plants yourself.
I'm sure not everyone will agree, but that is what I've learned so far. I sure wish I had started with all of this info. It would have saved me a lot of headaches at this point.
Good luck!