Korean past and present tenses

I really enjoy the book I am studying from. It is called Korean Through English (Hollym Editions). I bought it in Seoul on a whim and I'm really glad I did. Each chapter is short enough and focuses on a couple of grammatical points and about twenty new words. It creates a nice pace to study.

At the same time, I can't believe it's already introducing the past tense and I'm not even halfway through the chapters. I think it's great as it helps to differentiate past and present, but I don't feel comfortable with present verb endings yet, especially the ones that end with a consonant or anㅣlike 오다 that turns into 와요  or 마시다 that turns into 마셔요. If I am writing slowly and I have time to think, then I might get it right, but if I start to speak then I lose my nerves (even when all this talking is just me alone in my room!) and I just add 어요.

I think I will create a spreadsheet with the verbs I know so far and what their ending is for the present tense and the past tense. Hopefully this will help make more sense of verb conjugation soon.