right then im new here(please dont get annoyed at me). ive just bought my first car

its a 1997 ford fiesta 1.25. ive looked at a few websites for new parts what they do and what knock on effect this may have on the car. when driving my car around i feel like a very slow moving target

so this is why im trying to get my car up to speed. i am learning the machanics trade so changing parts shouldnt be a problem i just need some very very good advice.
1) what parts should i change.
2)what would boost the performance the most.
3)£££££ roughly the price and where to get it from
4) IS IT REALLY WORTH ME DOING THIS!!
any help from you guys would be great....thanks