On one hand, long and ugly affiliate tracking links are a straight giveaway to people that you want to sell them a product (and people may be uncomfortable clicking on them). Therefore, making your link shorter and "nicer" looking will it give a more professional appearance. One of my favorite plugins for making links look "pretty" is the Pretty Links WordPress plugin.
When you promote a product you also promote the person or the company who is behind the product so try to choose wisely. You don’t want your visitors to go and buy a product following your advice then come back unhappy. Do you think that this visitor will come back to your site and take your advice again? Most likely no; this can hurt your credibility in the long run. Usually, websites/company that offer good customer service will have better customer satisfaction so try to stick with promoting their products.
Very nice article! Affiliate marketing is perfect for bloggers as long as they offer quality content and are upfront about it. If people are willing to donate money to YouTubers via Patreon, why wouldn’t they buy something that they want or need through the site or blog of someone that offers them great content and support his or her efforts? It’s a win – win kind of deal.