In a world where extroverts are considered the norm and introverts are considered abnormal (even if not deliberately), one result is that whenever I do take time for myself, I feel guilty, especially if I'm deliberately bowing out of a social activity to take time for myself.
So here are a few helpful introvert tips that help me to feel better about it.
1. Be open about yourself from the beginning. The more open I am about my introversion to those around me, the easier it is to explain to those people when I bow out of social situations. I have a group of people know who understand that I will only participate in activities with them about half the time they ask me to... and they're OK with that, and are willing to explain that to anyone else who asks why I keep to myself so much. Making allies is great.
2. Plan out your social time. Sometimes introvert guilt will push me to go out and spend social energy I don't have, and I suffer for it. I become cranky and unfocused, and all because I talked myself into deciding, "Well, I can go out and do this tonight." Now I plan it all out. At the beginning of the week, I tell myself that I will go out 2 times this week (maybe just 1 if it's a stressful week) and then I stick to that. If I know there are specific activities I want to attend - birthday parties or movie nights with friends - I schedule that in. Otherwise, it's open for spontaneous social gatherings. And if I don't go out twice that week, that's OK, too. It's easier for me to go along with a self-imposed limit than to judge on a case-by-case basis whether I should go out or stay in.
3. Find compromises. Best compromise: Coming back home early. Drive yourself whenever possible. Then you can make the rounds, spend a little time with everyone, and make your way home when you feel yourself starting to fade. If I can reassure myself I've put at least a little time in, it's so much easier to head back to my quiet time.
4. Remind yourself why you made this decision. Sometimes when I'm feeling especially guilty for not spending time with people, I think, "Well, I should be productive! Because then I won't just be sitting around doing nothing." The thing is, this does nothing to assuage the guilty, and frequently I have trouble even being productive because I feel pressured to get so much done to prove to myself that it was a good decision. So I started rewarding myself instead. If I felt guilty for bowing out of a specific activity, the first thing I'd do starting my alone time was watch an episode of my favorite TV show, or read a book, or turn up music and sing along to it. Something that reminds me how much I love doing things by myself. Something that reminds me how much I needed this. Something that overwhelms the guilt with delight at being alone. Then I can go ahead from there and be productive if I want... or I can just enjoy being alone.
Introvert guilt can be difficult to crush, and I still have a tendency to apologize to people when I choose alone time. (Or tell an introvert lie.) But these are some things I've found to help me not only embrace my introversion, but embrace it boldly, without feeling guilty that I just need more alone time than other people. Because that is OK. And I am not about to let misplaced guilt take the joy of solitude away from me.