Ditto: "DO NOT SIGN ANYTHING WITHOUT PROPERLY REVIEWING IT."
If you aren't _completely_ confident that you understand contract law, then the instant they hand it to you just politely and pleasantly say "Thanks - I'd like to run it by my attorney" then split the scene completely.
If there is anything I regret about my career it's that I've signed ill-advised contracts.
Don't listen to any excuses about how "it's our standard contract" or "it's just boilerplate".
What that contract actually means depends on the presiding jurisdiction, for example in California Non-Compete Agreements are unenforceable; I expect that's the case in some other places but by no means all of them.
Even if you don't really have an attorney, claiming that you do will enable you to take the time you need to puzzle over the contract without them breathing down your neck.
If there are specific clauses that you do not agree with, draw a rectangle around them, an "X" across them, then your initials and the date in the margin.
If they simply will not sign the contract themselves after you've done that then my advice is that you get up and leave.
Twice now I've been presented contracts that specified that I assigned the employer all of the IP that I had ever developed. Not during the time of employment, but previously.
For example when I was five years old I worked out a novel and unobvious way to tie my own shoes. Those two contracts would have assigned my shoe-tying technique to my employers.
One of them I flatly refused to sign the contract, but was hired anyway. On my last day - after doing lots of good work - I signed a very normal NDA.
The other I Xed out the clause that assigned my IP. They were OK with it and countersigned it.
Make sure you have two identical copies of the contract and that you and they sign both - that is, if you sign anything at all. Take one copy with you afterward.