This chapter is universal tho, you can apply this info in any strategy/build, if you want to jump on imperials and combos just go directly at Draven chapter.

Starting
At first carousel you have a lot of cheap champions to chose from, you should pick based on the following:
- a pirate that you will keep until mid-late game
- a champion you want to sell with first ocassion that have a good item like bow or mana.
Priorities
First of all, don't be afraid to lose a lot of early games, that is acutally a big advantage since you will have priority on carousel so you will be able to choose better items.
Everytime at carousel you should look for the highest tier champion that posses an item you want, because selling them will give you more gold, if there is no good item just go always for highest tier, if there are some good items but low rarity champ you should go for items insead.
Only exception for that rule is when there is a champion for your late team comp and have an item that can be used (ex: Draven with bow, tear, negatron, bf)

Early Team
your early-mid game team should always contain 3 pirates, as they will provide a good gold sustain and usually they work good with gunslayers a.k.a a 2* tristana, 2* graves, 2* gangplank and another 2* pirate should mentain your HP just fine until you finish or almost finish your desired team.
Sometimes you will be forced to throw pirates away and go with what you have finished until that point, if your HP is below 10 there is no point to risk unless you are certain you will win the match.
Items
Early you should build only items you want to reuse on some important champion of late game (ex: Rapidfire Cannon on tristana to later give it to Draven, Frozen Heart on kassadin to give it later on Leona, etc.)
Do not waste items early, those matchs are not important at all, the single one you want to be sure you win are the pve ones that may give you some more items or gold.

So excuse my Draven but everything I said is legit, even if Draven got some nerfs before even launching, he is still Draven, and with any BF items he will deal tons of damage, and outdamage every lv2-lv3 at level 1.
The best way to Draven him out is to Draven his dravens into field (swain, katarina and darius) to get the maximum dravmage.

Imperials works great with nobles (ironic) if you would be somehow able to pull them all out, but in an ideal case is a 6 (nobles) 2 (imperials) and hope the imperial bonus will land always on Draven.
Dont get me wrong, Darius is a great frontliner, and Swain a great .. well mostly damage in that comp. Katarina, is just katarina, basic assassin, her potential is to limited on enemy items, positioning and rng.

Other combination would be shapeshifter demons, which maximize swain potential, he being demon and shapeshifter. You don't need to go full demons, Elise alone will provide you a trait bonus, and with Shyvana or Nidalee your swain will become tankier when transform. This total is a 7 units combo, from which you can in late go for more demons or guardians.

Glacials are good too, but expensive, dont forget to bring some guardians to make draven more draven alive if you get a braum in a glacial setup.

Blademaster, litereally they are only for Draven, and help for nothing else.

For Swain best item is Morellonomicon for damage, and Warmog's Armor if you use him as a tank (shapeshifter trait works good with it and can keep him more alive, but pure ap can do it too), for even more sustain you can go Hextech Gunblade. Pure utility items (if you dont have someone better to place them on) Frozen Heart (better on darius tho), Zeke's Herald if on same line with Draven , Redemption

On Darius depend more of how you use him, but Frozen Heart will be always a great choice since he will be the frontliner, any def/sustain options are good on him, but don't overcharge him with pure utility and no sustain since he need some tankiness to remain alive enough to spam his skill.

Bloodthirster is Draven best friend, this single handed can be enough to make your Draven a viable carry, but ofc there are more items if you really want a carry, a good option would be Rapid Firecannon or Guinsoo's Rageblade to increase his dps and a defensive one like Dragon's Claw (if they are focused on spamming skills) or Phantom Dancer Also, spam Zeke's Herald around Draven's allies to make him hit faster without wasting his slots

Just give her a Morellonomicon and Seraph's Embrace or Spear of Shojin

Except imperials Draven works just fine and solo, acutally the most cancerous team you may build is a team full of tanks (include Darius too just to maybe give Draven some extra damage) and a Draven in the middle, some recommandation would be Leona and Braum (really close to Draven for stack armor), Garen and Kayle (with leona will give (3) Noble bonus, that may give Draven or anyone 60 armor and 30 on hit heal) and well, anything else you find. Sejuani is pretty good for aoe stun, and if you have spatulas for a glacial trait you will be even more dominant. Another nice tank would be Shen for his aoe dodge.