General

If you didn't know, Silver III is better than Silver IV
Also, simply because you're in the Silver division, you CANNOT rely on your teammates carrying you. If you want to guarantee your win, I suggest you play enough normal games to be able to carry or if you think you can already, carry your hardest in Silver division.
Most important tips are also taking objectives and map awareness. No matter how good you are during the laning phase, if you don't have those 2 I mentioned, then you will lose no matter what.

Silver 3 > Silver 4. Anyways, my advice is not to blame others if you lose. Just do what you think needs to be done by you to give your team the best shot at winning, you have to rely on others to do some things right, but leave as little room for error on your end as possible.

Map awareness, Last hit, Don't do anything stupid, take OBJECTIVES, Make logical/rational decisions (if they're all at top, push bot/mid take dragon.)
That's all you need to stay in silver. If you want to get to Gold, you have to work on mechanics.

EDIT: Oh and also don't flame as the guy below me said.

Press R to win.

last hit

buy wards