Whilst the spandex does dazzle, a couple of simple upgrades make a lot of difference and costs very few certs. In fact you should get enough in an hour or two's play for the very basics.
It helps to try all the 'professions' and see which one you like most. If you spread your spending across them all, it takes a long time to make a really appreciable difference in any of them.
Once you have decided on your main profession, there are some very cheap upgrades that make a big difference. Forget weapon upgrades to start with, the starter weapons are all at least ok and in some cases very good. Upgrade shields first, I believe nanoweave armour is considered the best, with flak armour if you want to concentrate on an engineer.
Grab a scope for your gun, I find the 1x reaction sight pretty good or the nightvision scope which makes targets really easy to spot. Neither are any good if you want to go sniper though.
That should be enough to get you started. I'll likely be on after I get back from swimming this evening if you fancy another go.
