Plenty of direct sunlight, plenty!
Autos are not known for growing very big outdoors, hence the need for the sunniest spot you can find.
Personally I would advise against autos outdoors and stick with normal feminised photoperiod plants if you are after yield. Some Indica dominant strains are just as quick or even faster than some autos and will out yield autos considerably. With the seeds available today, whatever you did 20 years ago will work just fine now. Leave the autos for indoors where they can be given 18/6 and perform to their best.
Any respectable fertilizer company which makes nutrients for cannabis will work, they all do the same thing basically and are all performers, but using half recommended strength is usually plenty strong enough. Whatever you do, do not defoliate your plants, they need each and every leaf they have to make the energy they need to grow their biggest and fastest, and no topping of autos either, a bit of LST is/can be advisable though.
Just remember -
Maximum amount of healthy green leaves = maximum energy production = maximum growth.
Besides, if your plant did not need those leaves, it would not have grown them in the first place!
A bit of well considered "lollipopping about half way through veg and a tidy up at the onset of flowering will help avoid small inner flowers, but is not necessary, often letting your plants do their own thing is best.
For autos, planting them directly in their "forever" home/final pot of around 15 litres works best, this avoids any transplant "shock" which may occur and ensures an uninterrupted growth cycle while in vegetative growth. This is very important, you need your seedlings to grow as large as possible before flowering commences automatically around weeks 3-6. Starting them in ridiculously small paper cups will stunt their growth early, leading to smaller plants and this is why planting them in their final pots from day one is recommended, due to unhindered root growth. Also, make sure to fill your pots right up to the top. More soil = more roots = more plant.
Photoperiod plants are best started in pots roughly 4 inches across and 5 inches deep, then transplanted into their final pots (20+ litres) about 3-4 weeks old or when they have 3-6 nodes already.
Be patient and don't try and force growth, the risk of burning them while little with too much nutrients is very real and this can set your plants back considerably, hence the suggestion of half strength or even quarter strength nutrients, especially when small.
Most brands of fertilizers are available via eBay or similar sites, although grow shops will have the best assortment.
For new growers I would recommend a few types of nutrients, but some of my favourites for the new cultivators are, Bio Vega and Bio Flores made by Bio Canna, or Organic Grow and Organic Bloom made by B.A.C., or Flora Nova Grow and Flora Nova Bloom made by GHE. All are excellent and simple to use, as there is no real need to buy anything else, just one bottle of "grow" and one bottle of "bloom". There are many brands that have nutrients whereby you have to mix part A with part B or even part C, which is just confusing and tedious. All the nutrients I have recommended are quality, a bit pricey, but highly concentrated, meaning one bottle of each will last multiple grows or many, many plants.
If you are really keen, adding a P/K booster during flowering can help, as well as some cal/mag every 2-3 weeks. Also giving some humic/fulvic or amino acids really helps, and giving all 3 really, really helps get things growing. Top dressing your pots with pure worm castings every 2-4 weeks is also beneficial, a cup or two around the plants once established works well. Just water in and your plants will love you.
For the final tip, "Mykos" made by Xtreme Gardening is a root fungus that is added to your soil mix and these mycorrhizae boost plant health incredibly. After doing some test with this product, I am convinced beyond a doubt that this or similar products are now an essential inclusion in each and every grow that I now do, and it works with all seasonal plants, not just cannabis, in case you want super tomatoes! Again, this product is a bit costly, but worth every cent, but you do not need to use much, making it economical in the long run. eBay has this product too.
Getting your watering right is where a lot of people struggle, watering deeply and thoroughly to run off every few days is far better than giving small amounts of water often. Your soil needs moisture from top to bottom to allow for good root development. Wait until the top 3-6cm is dry again before watering again. It is vital to have run off, that is, having water exiting the base of the pot, apart from assisting good root development, it also helps prevent nutrient salts from building up in the soil to toxic levels and burning your plant. Once this condition occurs, it is virtually impossible to correct in soil successfully.
Your seedlings will not need any type of "humidity dome" or other hyper humidity causing contraption, cannabis is not a rain forest plant, neither is spritzing the leaves necessary, this can cause fungal problems and is pointless.
That is roughly it for a good starting point, just don't be too critical on yourself, mistakes will be made and are a normal step in the learning process and never compare your results with anybody else's, what they are doing and what you are doing is two completely different systems and results will differ greatly.
Also, plant a couple of more seeds than you think you will need, not all seeds will hatch and not all hatchlings are normal/healthy, so a couple of spares can come in handy.
Congratulations on your new (returning) hobby, it is an endless process of learning and extremely satisfying to be able to harvest home grown flowers for which you have had total quality and health control over, with no chance of nasty chemicals or other poisons. And the best thing is that you won't be funding anybody else's retirement plans or facilitating a questionable underground market that cares zero about you or your health.
I have been enjoying this personal medicine hobby for 35+ years and still learn something each and every grow, and still make mistakes, but nothing too major anymore (hopefully!), so go easy on yourself, and like I said earlier, results will come, and with more experience, the more refined the results.
Good luck and happy growing,...........
Organoman.
P.S. - as a personal recommendation and for exceptionally easy to grow, stable and potent plants, try "Sweet Seeds", their genetics are outstanding - all of them! I love them all and never had a dud. They are now my "go to" breeder!