Hi Welverin and welcome to the hobby and good to see another greenskin join the battle against those stinkin' umies' an uva pretty boyz.
speed freaks are always a good start with the battleforce as you already get a trukk and some bikes. with the bikes you really want to use them as nob bikers as they are one of the toughest most versatile units we have. regular warbikers tend to get crushed pretty easily i find. in a 1500 point army you would look at maybe between 4-8 of these depending on how many points you want to spend on them 1-3 power klaws and some big choppas as their load out is pretty good. but make sure you got a warboss on a bike to ride with them.
trukks will be your main assault carrying your boyz into the fight i usually run between 3-5 trukks at 1500 points depending on whether i use nob bikers or nobz in a battlewagon
trukks are bare bones or at the most with a ram for terrain re-rolls don't worry about any other upgrades for them in my opinion . and your load out should consist of 11 boyz (i prefer sluggas and choppa's because my idea of trukks is to get the boyz in to close combat asap) and 1 Nob with a Power Klaw and a boss pole to keep them inline
war buggies and defkoptas with twinlinked rokkits are always nice to have roaming around as anti tank. but are not essential.
some loota's are always good to have as they can deal with most armour and your best bet at flyers if you don't have flyers yourself.
burna boyz go well in battlewagon's as many people will attest too.
and also a bigmek with a Kustom Force Field will always help with a 5+ cover save for your vehicles.
to give you better idea of some speed freak lists, do a search in the forum search bar for 1500 speed freaks and you will see some variations on the lists to see how you want to go.
hope this helps