Without giving us too much information on your playstyle, it's sort of hard to help you. Anyways, here's some general advice:
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Don't push the wave unless you know that you are either safe from early ganks, or you have an advantage on the enemy and know that their csing under tower is abysmal (Swain, Fiddlesticks, etc.) This leads me into my next point...
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**Know the matchup.**As some dude named Joe once said, "knowing is half the battle." Make sure you know the enemy's champion (Cooldowns of Spell, Duration of CC, Damage, etc.). You can brush up on your game knowledge by checking the lol wiki during the loading screen. Just playing the matchup and having experience helps a ton, too.
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Use your trinket in the early stages of the game to ensure safety from level 2 jungler ganks and the like. When you are jungling, you can also use it to ward around your buffs.
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Don't fight in an enemy minion wave. I cannot stress the importance of minion control in the early game. When you are only level 1-5, minions do a lot of damage if you let them attack you for a few seconds, which will mean losing the trade. Additionally, keep watch of when the next minion wave is going to appear. Don't start trading with the enemy when their minion wave is going to appear before yours.
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There is no shame in keeping close to your tower. If you know your early game is terrible, whether as a player or a champion, sticking close to tower is a very viable strategy. If you keep close to your tower and stay within experience range, you'll lose out on gold, but still keep up in levels with your lane opponent. Losing a little bit of gold is better than giving your enemy gold for killing you.
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Don't fight on the enemy's terms. Basically what I'm trying to say here, is that if an enemy is walking up to you, wanting to trade, that probably means that they believe they have an upper hand. Logically, no one would engage on an enemy not believing that they can win. This either means that the enemy knows that they have a certain spell up and you don't, their minion wave is bigger than yours, or their jungler is waiting for a gank. More often than not, if the enemy starts acting differently, that means they know something that you don't. Never fight these.
I think I covered quite a bit of good information. I'm only Gold IV atm, so I'm not the best player, but I hope these tips can help you out.
P.S. Make sure you have a full Rune page, and that your Masteries are allocated correctly. Some of the flat stats that you gain from certain Runes and Masteries can make a great difference in the early game. Seeing as you're only level 25, you can't have a full mastery page, but you have access to tier 3 runes, so make sure to stock up :D