Never Choose a Hyper-Roll Composition
A bad start is considered when you have a weak early game composition, lacking essential items or a strong carry champion. Meanwhile, hyper-roll compositions require you to have enough items for your carry (like the Rod of Ages for Ziggs or Infinity Edge + Bow for Xayah), so it’s best not to dream about golden compositions because even if you can build them, you won’t have the items to make them strong.

The best composition to choose when having a bad start is the “Power Level” type, which means using levels and expensive carries to win. The reason is that with a bad start, you will continuously lose and have a stable amount of money from the losing streak, the best way to use that money is to invest in leveling up to get more champions in your composition and prevent excessive health loss, rather than just rolling.

Use Strong Units Immediately
Returning to the initial situation, when you have a bad start, you currently have a lineup of 1-star champions, with a few reaching 2 stars, and you are falling behind in the match. What you need to do now is to look for strong “hired” units to minimize your losses, with names like Jayce, Graves, and Darius being the best options in that case.

They have high base damage, good effects, and are strong enough at 1 star to take down many enemy champions without causing you to lose your losing streak. Moreover, the mentioned units can use any items, so you can equip items for them early, even those meant for your future carries to be strong immediately and withstand enemy attacks.
Leverage the Advantage of Losing Health
Teamfight Tactics is a very fair game; if you are strong early and maintain health, you get to choose items first in the shared selection round, and conversely, the one who loses the most health has the best “delicious” items. Therefore, take advantage of this to acquire the strongest items that suit your composition to make a comeback in the late game.

The advice when you are low on health is to grab all the strongest items in the shared selection round, like B.F. Sword, Wooden Bow, or Giant’s Staff. You may not need those items immediately, but they are all useful items that can be combined into many powerful items. Furthermore, stealing those strong items is also a way to limit the strength of those above you.
Play Around One Carry
One piece of advice from a player with two top 1 Challenger accounts – MismatchedSock, is that when you don’t know what to play, stick to the first carry you have, even if they are 1-star champions. This is especially true for players who have to pivot continuously due to a very bad start because you won’t have enough money to play a composition with multiple carries or any strong team comp.

MismatchedSock’s advice is that he often prioritizes Kayle/Jinx/Irelia and Jhin as carries when losing too much health. They are all strong champions, with stable damage and not overly reliant on their traits or origins, so you can use items, particularly those obtained from the shared selection round, to compensate. At that point, you will have a huge amount of damage at a low cost and, most importantly, it will be available immediately.