With galio, make sure you take a mana regen item. Prioritize gust>smite>bulwark (just for the early game). Use gust to pick off near dead minions from range to try to keep your xp up and then nuke the caster minions hard and fast when at your tower. And of course, line gust up to put in harass when you can, but the priority is to control the minion waves to keep your tower from getting pushed too fast so your jungler has time to help.

Just sit in the back and wait for the right moment. Hug your dam tower and yell at your jungler to come gank as soon as he can and you should be fine. Middle lane and jungle should be ganking if they are pushing your lane. Pack pots and hug tower til the gank comes easy as that.

I 1 v 2 with Xin Zhao all the time. His passive heal makes it so he can stay on your tower indefinitely with minimal ganks. There will always be bad combos but I rarely/if ever get killed 1 v 2. 1 v 3 gank is roguh but if you control creep position so its at your tower you're fine. Once there you counter their natural pushing(2 ppl) by autoattacking to heal and farming last hits.