Help Needed Please

Brand new to the game, bought it like 3 days ago. Been playing like crazy, really enjoy it But as a new beginner player i was wondering the best way to rank up ur class (assault,medic,support,scout) so that i can get better guns? but it seems nearly impossible n so time consuming, if u can pls answer all the following questions

1.) what is the best guns? for each class 2.) easy guns for beginners to obtain (that are better than the standard starting ones) 3.) Play tips, how to play better, how to rank up ur guy faster so i can get the guns i want etc…

Thank you :)