I will be using LocalBitcoins, if I have 0.5 BTC I can sell up to 85% of that in my own advert then the rest on another person's advert. Is there a way to make a profit this way? Or is 0.5 simply not enough to start with?
0.5 bit it is not enough but it is normal amount, so should try it and guess you can continue trading or not, but the result will tell you, if you can handle trading and make profit than no problem in it, But main problem is that trading is not easy as we think that, when we start it than we know trading is really difficult to make profit from it.
"Real" traders usually start with accounts in the 5-6 digits. So I highly doubt that a lower 3 digit account will get you anywhere close to success. With such little money, you can trade for the sake of the experience itself. Learn strategies, get to know the markets, spot opportunities so you're armed in case you once have enough money to start a trading account.
Especially if you're planning to start trading shitcoins, your average losses are likely way higher than your gains, because you're depending on the goodwill of usually only one single pumper. If he decides to make money, you get an opportunity, but even there, the chances of missing out on this are extremely high.
To make any substantial gains using Bitcoin only, you need some breath. Bitcoin is not as volatile as earlier, anymore, and the timeframes between the buy- and sellpoints grow larger and larger.