First year analyst advice

Not sure if you meant to post in the RE forum if you work in IB, but I'll bite. 

1. Don't make mistakes twice - Mistakes are perfectly natural starting out. What is NOT acceptable is making the same mistake multiple times. Create a checklist of things to verify prior to sending any model or memo for review. 
2. Ask plenty of questions - The first 6 months to a year in a role are your pass to ask semi-stupid questions. If you're still asking dumb questions after a year, it's a problem. Learn the basics now and get your routine down to get into a rhythm with deals. 
3. Think - analyze the project as if you're the only one working on it, and you'll be the only person reviewing before sending to a client. You'll catch a lot more mistakes, especially the obvious ones that make you look dumb to superiors - look for numbers that just don't make sense. Try to have an idea of where the model will come out intuitively before you even start in Excel, and dig into why it's different than expectations.

There are 100 other tips, but I think if you get these down your boss will only be left with invalid reasons to dislike you. It sounds like your head is in the right space by trying to improve, so if your boss genuinely just doesn't like you without good reason, don't beat yourself up over it. Just get your work done and do it well.