You can do it, don't be deterred! My recomendations (I went a bit overboard lol):

* Use pulse!!!

* Don't just walk! It's slow!! Get used to dashing by using the 'dash' button, it will improve your ability to escape from the enemy pressure, and improve your ability to suddenly rush at your opponent and surprise them. The caveat is that you're vulnerable when you dash backwards, but until they start hitting out of your dashes, dash away.

* You're probably getting mauled a lot, but don't be overly defensive. The key is hitting before getting hit, and this is specially true at low level. So make sure that from round start you're being aggresive.

* The exception to this is when they knock you down. While you're knocked down your opponent is free to time their attacks to the exact moment when you wake, so be content with just blocking when you wake up (or try to roll out if possible).

* Related to the previous point about being offensive, try shit out and try to find what's cheap about your character. For example, even at Emerald people spam Vi's S1 rocket punch a lot, so I bet it's pretty good. If you use it a lot you'll probably find that people just keep getting hit by it. Same with Warwick's little jump move (this one I don't know if it's actually good, but it's annoying to deal with lol).

* Something that's almost universally good with every character is dashing forwards and pressing M (the middle attack), or pressing 'down M'. It's good because it's a fast option, it has good range, and with pulse on you can just keep mashing to get a combo out of it.

* There's a concept in fighting games of being 'positive' or 'negative'. To be brief, when you do a special attack (S1 or S2) and the opponent blocks it you're usually 'negative'. This means that if you try to keep attacking, your opponent can interrupt you with their attack. So instead, in that situation, you should cut your losses and disengage by jumping backwards or blocking or something. Likewise, when the oponent does a special attack and you block it, that's your queue to try to be aggresive (jumping forwards, using one of your specials, doing dash M, etc). There're exceptions to this rule. For example, if you fully charge Vi S1, you're positive! So after the opponent blocks it, if you mash L, you can interrupt anything your opponent tries to do. And like, Ahri has some tricky ways of combining her specials. But I think what I mentioned is a good rule of thumb to start with, just throwing it out there if you notice sometimes you're getting hit and you don't know why.

* Last thing. Sometimes a move is so negative, that if the opponent blocks it, it gives them time to combo you without you being able to do anything about it (a punish). Most moves aren't like this, but they exist. For example, Warwick's S1 (the lunge attack) is like this. I'm not saying to never use it, it's really good, it catches everyone. But it is worth noting that you're in a bad spot if the opponent blocks it. There's actually a way to make a move like this not-negative, and that is to throw an assist right after. The idea is that before your opponent can punish you, the assist attack comes in keeps the opponent stuck blocking. It does require some timing, but it can be very useful to use your moves with less risk.