Etherdelta might not be the most user friendly plattform so to speak, but they do have an advantage when it comes to listing new, promising projects. At the same time, it was compromised at one point, and some people where loosing their tokens. Still if you are using caution, it should be fairly safe I would say without knowing all the technicals.
Using your ledger (it's out of stock until 20th of march ref. my prev post) I would say, is the most safe, and also convinient way to connect to etherdelta.
First, go to settings on the ledger and turn on Contract data and Browser support.
The adress that will connect to Etherdelta is the first adress on the list (you have multiple Ethereum adresses on the device). To get this public key (adress), yu go to myetherwallet and click view wallet info, and choose Ledger Wallet.
The first adress on that list will be the one connecting to the ledger. You can now send some eth to this adress that will be used for both gas and for purshasing the token of choise.
Now, you can go to etherdelta in the browser, and if the ledger is connected, it will automatically connect to etherdelta. If the ledger is logged out because of inactivity, just activate it with the pin, refresh browser, and its connected.
Here comes the first frustration with etherdelta. If you just sent some eth, and it shows both if you log in by myetherwallet and etherscan, it might take another 10 minutes or so before it shows in etherdelta. But when it does, you can make the deposit. I presume one has used etherdelta before, so I'm not going into all the detail on the basics there.
Here comes the convinient, and "feelsafe" about using your ledger. When making the deposit to etherdelta you chosse the amount of eth to deposit, and click deposit as usual, and for etherdelta to do this, because you haven't given up any private key (it never leaves the ledger), you confirm physically on the ledger. It will display "confirm transaction", and there you go.
Some notes: etherdelta does seem to have some issues and bugs, so you will get some feedback that you don't have enough eth to gas and so on, still the transactions are being made, don't make the tranfer again because of these messages. To easier cope with this, and see what is acctually happening, open etherscan for the adress you are using in the tab besides and you can monitor the movements and trades there.
Hold of 1 hour the first time you are doing this, seriously. 40 minutes if one has done it before the way things are now. Lets hope the etherdelta team will improve the experience soon.
For convenience/ security measures I do transfer the tokens to other adress than the one that is used to connect to etherdelta, just lets some eth/ gas stay there. Probably not necessary, but it just feels better.