Many questions!

[Star_Rider]

Ok, first I have 20L, not watered, or cycled or nothing yet. Gonna use sand substrate, so any advice or things I should do with that are welcome. Not sure if I'm gonna use real plants or not..

Gonna do a fish-in cycle, with some guppies I'm gonna get from a friend as well as some water and some gravel from the tank. Anything else I should know for doing a fish cycle?

I think thats all for the moment. Dont need to worry about what fish to put it in till its, later on.. But any general info wanna throw, go ahead..

I'm not really a beginer, I just haven't cycled a tank in a long while, nor one of this size, as big as this, so yeah.. Hi! =P

if you are adding some gravel from your friends tank you may jump start the cycle process.
the water from their tank won't help...much.
keep tabs on the ammonia,nitrite and nitrate.
if you can see if you can get some media from their filter..maybe a dirty sponge or something from the existing tanks filter. this will help jump start your tank a bit faster.

 

[shawnhu]

well I dont know... to me seems easier to do a water change everyday, feed fish, look at test strips.. then to remember to add ammonia once a week, and all that.

Let's do a little math.

Fish-In Cycle checklist:
1) Feed fish
2) Take out test strips
3) Take out water from tank for Test strips
4) Dip Test strips
5) Read test strips while it drips all over
6) Dry hands because you dipped the test strips
7) Mop the floor from the test strips dripping
8) Do water changes, as much as 50% per day
9) Mop the floor again because you changed the water and the hose fell off
10) Think of what to do with the 1/2 dead guppies that's been burned through the cycle process

Fishless Cycle checklist:
1) Add a few drops of Ammonia once a day, for 6 weeks.
2) You're done.

Now you do the math.

 

[AfroCichlid]

Add your plants as soon as you have water in the tank. They will help remove harmful chemicals from your water. As others have mentioned, look into alternatives to ordinary sand, you will have more success with plants using EcoComplete or alternatives.
Avoid the temptation to add your fish right away. Even though you plan on doing a fish- in cycle, you should still wait a day at the minimum after start up. Set up, do your planting, and start the filters.
As others have mentioned, you should have a good liquid testing kit. Minimum tests should include Ammonia, Nitrite, Nitrate, and pH. You'll want to test these parameters every day. Ammonia quickly builds up in a new tank. I would plan on daily water changes of up to 50%-75% for a few weeks. Not too bad in a 20 gallon.