linking to your sites.

Exchanging likes is a bad thing as search engines dont like this kind of thing. Quality backlinks depends on many things and one of them is when they link to you but you dont link to them. Link exchanges are a thing of the past

what other methods can you suggest ?

whcih one works best for you?

I don't agree with any of the answers given here. It certainly is not blackhat and it is very useful to interlink with other sites in your niche. If for example your website is a travel guide on Paris then it is very useful to link to other great resources on Paris and have them link to you. In fact this way Google knows that you are in the Paris niche and much liked by other authority sites in the niche.

It is important of course to have links on quality websites, but as suggested here that has nothing to do with pagerank! Look at the website and see it really is a good resource and if it is updated regularly, don't mind about page rank but look for quality yourself. Most of them will have a good PR anyway if they are really quality websites (or will get PR in the future).

DONT buy links but manually build them yourself, so you are control on which websites you appear. If you have great content, you will get a lot of positive responses and most of the time they don't even ask for a link back!

for example i still use link exchange method and it really works. Only thing is that you should not do too many link exchange.

Exchanging links is bad practice from SEO point of view. You can get backlinks from other quality portals like hubpage, ezinearticles, stumbleupon, tumblr and like this many more. The thing is, you need to be clear and informative with latest updates in spectacular field.

Don't go for link exchanges, It comes under black hat SEO. Just follow natural link building technique, theme relevant submission on good PA and DA website. This will increase traffic and SERP of the website.

Exchanging links is black hat and even if you manage to escape google updates like panda and penguin, you will be slapped with manual penalty when you reach page 1 with those links. So avoid using this very old method. This method will increase your rankings but does not help in the long term.

Link exchange is a very old method and it is not a good way for generate backlinks.
There are many methods you can use for generate quality backlinks like,
(1) Social Bookmarking
(2) Forum Posting
(3) Blog Commenting
(4) Directory Submission
(5) Blog Posting

Its, a bit risky, but its not something you will get punished for right away, since good bloggers do it all the time without any seo intention. they recommend their followers to check out bloggers that they know and recommended on each other.
It gets risky when you do it wrong thought.

I fully agree with you guys, that link exchange is risky one and not for long term use. But if you will be careful and still don't exchange too many links this method might be worth of trying for small websites.