>>361314958
Armor and helmet is the most important buy because there's no other way to get it, however no-one buys for each other so sometimes its better to buy a gun instead. Clippers are very important on the defusing team and often are the only difference between a won and lost round. Other than that, buy whatever gun you like; no-one uses grenades like in CS so it's up to you whether you buy them or not. Most attachments will reduce payout for kills, as well, so bear that in mind if you are struggling to afford anything.